ARM: Generalize armv7 as arm.

There are ARM systems which are essentially heterogeneous multicores where
some cores implement a different ARM architecture version than other cores. A
specific example is the tegra124 which boots on an ARMv4 coprocessor while
most code, including most of the firmware, runs on the main ARMv7 core. To
support SOCs like this, the plan is to generalize the ARM architecture so that
all versions are available, and an SOC/CPU can then select what architecture
variant should be used for each component of the firmware; bootblock,
romstage, and ramstage.

BUG=chrome-os-partner:23009
TEST=Built libpayload and coreboot for link, pit and nyan. Booted into the
bootblock on nyan.
BRANCH=None

Change-Id: I22e048c3bc72bd56371e14200942e436c1e312c2
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: https://chromium-review.googlesource.com/171338
Reviewed-by: Gabe Black <gabeblack@chromium.org>
Commit-Queue: Gabe Black <gabeblack@chromium.org>
Tested-by: Gabe Black <gabeblack@chromium.org>
118 files changed