virtio-net: Increase filter and control limits

Increase the size of the perfect filter table and control queue depth.
This should give us more headroom in the MAC filter and is known to be
needed by at least one guest user.  Increasing the control queue depth
allows a guest to feed several commands back to back if they so desire
rather than using the send and wait approach Linux uses.

Signed-off-by: Alex Williamson <alex.williamson@hp.com>
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
