qede: Prevent VFs from using XDP

Current implementation of VFs is very tight in regard to queue
resources. VFs support for XDP would require quite a bit of additional
infrastructure in qede and qed [sharing of queue-zones between queues,
more VF cids, mapping of the doorbell bar, etc.].

For now, prevent XDP programs from being attached to VFs.

Signed-off-by: Yuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>