rocker: Create an ordered workqueue for FIB offload

As explained in the previous commits, we need to process FIB entries
addition / deletion events in FIFO order or otherwise we can have a
mismatch between the kernel's FIB table and the device's.

Create an ordered workqueue for rocker to which these work items will be
submitted to.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/rocker/rocker.h

@@ -72,6 +72,7 @@ struct rocker {
 	struct rocker_dma_ring_info event_ring;
 	struct notifier_block fib_nb;
 	struct rocker_world_ops *wops;
+	struct workqueue_struct *rocker_owq;
 	void *wpriv;
 };