Remove redundant chapters, clarify and reword confusing sections.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>

Flashing U-Boot for Exynos 7870 requires creating a stub device tree,
where certain properties and nodes are defined which are populated by
the previous bootloader in the phones.

Since these properties are now available in the U-Boot device tree, it's
now possible to use the same blob generated by U-Boot in place of the
stub, when creating boot images. Update the build documentation to
reflect the same.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

U-Boot for this board is programmed to use the external DTB if an
internal device tree is not available. This makes it safe to build boot
images using the non-DTB U-Boot binary, while taking up less space.
Reflect this change in documentation.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

Since there is only one internal device tree allowed in U-Boot, the
DEVICE_TREE flag is required for building images for various devices.
Document it in the build guide.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

- Assorted updates

Document the image preparation and flashing techniques for
Exynos7870-based boards. This is done in a separate file in a
sub-directory, which is linked back to the main documentation.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

Add support for a generic platform which intends to support multiple
boards powered by ARMv8 Samsung Exynos SoCs. Some important features
include:
 * Fastboot: This is present to provide an open alternative to Samsung's
   proprietary Odin protocol. The board file configures certain features
   for fastboot, such as a dynamically allocated fastboot buffer, and
   standardized (lowercase) partition aliases.
 * EFI: Kernel image can be loaded from an EFI partition. This
   adopts a standard booting process, which multiple OS distributions
   can rely on.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

As stated in PXELINUX doc [1], the PXE configuration file has to be in
the format of "01-MAC-address" for Ethernet connections:

    The hardware type (using its ARP "htype" code) and address, all in
    lowercase hexadecimal with dash separators. For example, for an
    Ethernet (i.e. ARP hardware type "1") with address
    "88:99:AA:BB:CC:DD", it would search for the filename
    "01-88-99-aa-bb-cc-dd".

Indeed, PXE implementation in U-Boot looks for files like that, as can
be seen from this call chain:

    format_mac_pxe()
    pxe_mac_path()
    pxe_get()
    extlinux_pxe_read_bootflow()

Mention the fact that PXE expects the configuration file to be prepended
with "01" in the PXE section of E850-96 documentation. While at it, fix
some other minor issues in PXE section.

[1] https://wiki.syslinux.org/wiki/index.php?title=PXELINUX

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>

Add more bootloading details for E850-96 board. New sections cover next
topics:

  - Hardware configuration of the boot device
  - Flashing and updating the software (multiple methods)
  - Booting with Standard Boot (multiple methods)
  - EFI System Partition structure for E850-96
  - Loadable firmware (LDFW) note
  - Ethernet and USB Host Support

That documents all recently enabled U-Boot features for E850-96, which
can hopefully make U-Boot more useful for the users and developers of
this platform.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>

The Galaxy R (GT-I9103) and Captivate Glide (SGH-i927) are both Tegra 2
based Samsung smartphones released in 2011. They both feature 1 GB of RAM
and 8 GB of expandable flash memory. The key difference is that the
Captivate Glide has an OLED panel (contrary to LCD in Galaxy R) and a
QWERTY keyboard in form factor of a slider.

Signed-off-by: Ion Agorria <ion@agorria.com>
Reviewed-by: Svyatoslav Ryhel <clamor95@gmail.com>
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>