RDMA/cxgb3: Turn off RX coalescing for iWARP connections

RDMA/cxgb3: Turn off RX coalescing for iWARP connections

commit bec658ff31453a5726b1c188674d587a5d40c482 upstream.

The HW by default has RX coalescing on.  For iWARP connections, this
causes a 100ms delay in connection establishement due to the ingress
MPA Start message being stalled in HW.  So explicitly turn RX
coalescing off when setting up iWARP connections.

This was causing very bad performance for NP64 gather operations using
Open MPI, due to the way it sets up connections on larger jobs.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>