iw_cxgb4: advertise the correct device max attributes

Advertise the actual max limits for things like qp depths, number of
qps, cqs, etc.

Clean up the queue allocation for qps and cqs.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>