RDS: IB: add connection info to ibmr

Preperatory patch for FRMR support. From connection info,
we can retrieve cm_id which contains qp handled needed for
work request posting.

We also need to drop the RDS connection on QP error states
where connection handle becomes useful.

Signed-off-by: Santosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>