cxgb4: specify IQTYPE in fw_iq_cmd

congestion argument passed to t4_sge_alloc_rxq() is used
to differentiate between nic/ofld queues.

Signed-off-by: Arjun Vynipadath <arjun@chelsio.com>
Signed-off-by: Ganesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>