cxgb4: fix a NULL dereference

Avoid NULL dereference in setup_sge_queues() when the adapter is
in non offload mode.

Fixes: 0fbc81b3

 ('chcr/cxgb4i/cxgbit/RDMA/cxgb4: Allocate resources dynamically for all cxgb4 ULD's')
Signed-off-by: Ganesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>