[Libguestfs] [PATCH] aarch64: launch: direct: Use virtio-pci devices.

[Richard W.M. Jones]

As discussed yesterday:
https://www.redhat.com/archives/libguestfs/2017-January/msg00040.html
qemu and the kernel now support virtio-pci on aarch64.

It turns out that no changes are required for the libvirt backend,
since with libvirt 3.0.0 the same XML will switch to using virtio-pci
over virtio-mmio.  I have tested this on Fedora 25 with a
self-compiled libvirt 3.0.0 rc2.

However for the direct backend we do need a small change to stop using
virtio-mmio devices.  In fact this simply makes aarch64 more like
x86_64.

I have mostly tested this by running 'make check-release' but I found
a few (unconnected) problems with that so I'm still running the checks
on this one.  However it's a pretty simple and obvious change.  I did
check that the max-disks test passes.

Rich.