libvirt: Provide a port field for GlusterFS network disks

Some versions of libvirt (RHEL6's 0.10.2) require a port
specification with a GlusterFS network disk, or they reject
the disk with an "XML error: missing port for host" error.

Provide port 24007 as part of the disk specification.

Closes-Bug: #1254820

Change-Id: Iedcce32618813ed093b8e9aa8a69d1219b2118a5
Merge "libvirt: Provide a port field for GlusterFS network disks"