ARM: Overhaul the ARM Makefile.

The ARM Makefile was copied from x86 and then modified, and as a result it
was carrying a lot of baggage. On top of that, the extra complication made it
inflexible, and we need a lot of flexiblity in order to support the fact that
the Tegra124 starts on an ARMv4 coprocessor instead of one of the ARMv7 main
CPUs.

BUG=None
TEST=Built and booted on pit. With this and other changes, built and booted
into the bootblock on nyan.
BRANCH=None

Change-Id: Ia6ddc27619bdb51e152ad0c628ad6f3037c103ce
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: https://chromium-review.googlesource.com/171017
Reviewed-by: Ronald Minnich <rminnich@chromium.org>
Commit-Queue: Gabe Black <gabeblack@chromium.org>
Tested-by: Gabe Black <gabeblack@chromium.org>
17 files changed