iw_cxgb4: use the MPA initiator's IRD if < our ORD

The i40iw initiator sends an MPA-request with ird=16 and ord=16. The cxgb4
responder sends an MPA-reply with ord = 32 causing i40iw to terminate
due to insufficient resources.

The logic to reduce the ORD to <= peer's IRD was wrong.

Reported-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>