Rename download_ovmf to download_amd64_ovmf and add a separate
download_aarch64_ovmf for CLOUDHV_EFI.fd
Replace build_edk2 with download_aarch64_ovmf in aarch64 scripts
Update OVMF firmware tag to ch-1e1b96f126
Update CLOUDHV.fd sha1sum in sha1sums-x86_64
Add CLOUDHV_EFI.fd sha1sum in sha1sums-aarch64-common
Fixes: #7622
Signed-off-by: Saravanan D <saravanand@crusoe.ai>