Add support for GRUB2 on ARM64 architecture

ARM64 uses UEFI as a reference boot environment, so add all
the relevant bits to support GRUB2 on ARM64.

BUG=b/229863697
TEST=presubmit
RELEASE_NOTE=None

cos-patch: lts-refresh
Change-Id: Ia334b15e5f5ec218fac93e33ff661029c6d30e1c
Reviewed-on: https://cos-review.googlesource.com/c/third_party/platform/crosutils/+/32360
Reviewed-by: Roy Yang <royyang@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
3 files changed