futility: Add --arch=arm64 option to vbutil_kernel

vbutil_kernel already supports 64bit arm architecture,
but it just allows "aarch64" option. However other script,
for example build_kernel_image uses ARCH environment variable,
which for arm64-generic overlay is defined as "arm64".
So vbutil_kernel will refuse the call.

TEST=run vbutil_kernel --arch=arm64
Check that the "Unknown architecture string: arm64" is gone


Change-Id: I94c547d6b6940ab8c622a6b8cff49b5f83c1fcad
Reviewed-on: https://chromium-review.googlesource.com/1080529
Commit-Ready: Adam Kallai <kadam@inf.u-szeged.hu>
Tested-by: Adam Kallai <kadam@inf.u-szeged.hu>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
1 file changed