Updates to the JH7110 common description:
- add detailed overview of JH-7110 SoC and boot process
- revise descriptions of deprecated StarFive loader modes
- refresh build directions grouped with SPL debug advice
- reduce usage instructions into common methods shared by supported boards
- cite starfive_visionfive2 board maintainer description of StarFive loader
- cite published datasheets for ambient operating temperature data

Redundant/deprecated sections of each board doc are dropped accordingly:
- deepcomputing fml13v01
- milk-v mars
- pine64 star64 (also add inclusion of JH7110 common description)
- visionfive2

Signed-off-by: E Shattow <e@freeshell.de>

This patch is not as E Shattow authored it, but contains non-trivial
changes from Heinrich Schuchardt as well. The original author has
requested that this commit be reverted until the changes can be
committed showing which parts were authored by E Shattow and which by
Heinrich Schuchardt.

This reverts commit 4c105d2ae7b0f847668ff1ef6b410f63ab4290b7.

Signed-off-by: Tom Rini <trini@konsulko.com>

Updates to the JH7110 common description:
- add detailed overview of JH-7110 SoC and boot process
- revise descriptions of deprecated StarFive loader modes
- refresh build directions grouped with SPL debug advice
- reduce usage instructions into common methods shared by supported boards
- cite starfive_visionfive2 board maintainer description of StarFive loader
- cite published datasheets for ambient operating temperature data

Redundant/deprecated sections of each board doc are dropped accordingly:
- deepcomputing fml13v01
- milk-v mars
- pine64 star64 (also add inclusion of JH7110 common description)
- visionfive2

Signed-off-by: E Shattow <e@freeshell.de>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

Describe building U-Boot for the board and booting.

Carve out common information for JH7110 boards into an include.

Reviewed-by: E Shattow <e@freeshell.de>
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>