This cleans up U-Boot's toplevel directory a bit and makes the
architecture 'config.mk' file naming and location similar to board
and cpu 'config.mk' files

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>

Each arch should handle setting a proper default CROSS_COMPILE value in
their own config.mk file rather than having to maintain a large ugly list
in the Makefile.  By using conditional assignment, we don't have to worry
about the variable already being set (env/cmdline/etc...).

The common config.mk file takes care of exporting CROSS_COMPILE already,
and while a few variables (toolchain ones) utilize CROSS_COMPILE before
including the arch config.mk, they do so with deferred assignment.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

all arm boards except a few use the same cpu linker script
so move it to cpu/$(CPU)

that could be overwrite in following order
SOC
BOARD
via the corresponding config.mk

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>