this change makes bootblock and verstage built for armv7-m use generic memset,
memcpy, and memmove because arch/arm/memset.S, memcpy.S, and memmove.S are not
compatible with armv7-m.
BUG=none
BRANCH=ToT
TEST=Ran bootblock on Cosmos prototype board. Emerged all current boards.
Change-Id: Ie1df2525362ffc2e8438ff7bd5fad7629b0477de
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/225312
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>