Fixes packages for arm64 bootloader
Fixes packages for arm64 bootloader

Should install "grub2-efi-aa64 grub2-efi-aa64-modules" instead of
"grub2-efi grub2-efi-modules" for arm64

Change-Id: Iee3191b0944b3b862890d166a9d36bd592fe8f7e
Closes-bug: #1839816

openstack/diskimage-builder,switch-ch/diskimage-builder,openstack/diskimage-builder,switch-ch/diskimage-builder