This patch enables proper support for arm64 images by disabling VNC support
and adding several properties to the image in glance that are necessary to
boot correctly:
hw_cdrom_bus=virtio
hw_machine_type=virt
os_command_line='console=ttyAMA0'
Change-Id: I68c9a5e0e083af2f92875c3bdf70df750f6e4d8f