qemu: allow migration with assigned PCI hostdev if <teaming> is set

qemu: allow migration with assigned PCI hostdev if <teaming> is set

Normally a PCI hostdev can't be migrated, so
qemuMigrationSrcIsAllowedHostdev() won't permit it. In the case of a a
hostdev network interface that has <teaming type='transient'/> set,
QEMU will automatically unplug the device prior to migration, and
re-plug a corresponding device on the destination. This patch modifies
qemuMigrationSrcIsAllowedHostdev() to allow domains with those devices
to be migrated.

Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>