RDMA/cma: Do not query GID during QP state transition to RTR

When commit [1] was added, SGID was queried to derive the SMAC address.
Then, later on during a refactor [2], SMAC was no longer needed. However,
the now useless GID query remained.  Then during additional code changes
later on, the GID query was being done in such a way that it caused iWARP
queries to start breaking.  Remove the useless GID query and resolve the
iWARP breakage at the same time.

This is discussed in [3].

[1] commit dd5f03beb4f7 ("IB/core: Ethernet L2 attributes in verbs/cm structures")
[2] commit 5c266b2304fb ("IB/cm: Remove the usage of smac and vid of qp_attr and cm_av")
[3] https://www.spinics.net/lists/linux-rdma/msg63951.html

Suggested-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/core/cma.c

@@ -868,7 +868,6 @@ static int cma_modify_qp_rtr(struct rdma_id_private *id_priv,
 {
 	struct ib_qp_attr qp_attr;
 	int qp_attr_mask, ret;
-	union ib_gid sgid;
 
 	mutex_lock(&id_priv->qp_mutex);
 	if (!id_priv->id.qp) {
@@ -891,12 +890,6 @@ static int cma_modify_qp_rtr(struct rdma_id_private *id_priv,
 	if (ret)
 		goto out;
 
-	ret = ib_query_gid(id_priv->id.device, id_priv->id.port_num,
-			   rdma_ah_read_grh(&qp_attr.ah_attr)->sgid_index,
-			   &sgid, NULL);
-	if (ret)
-		goto out;
-
 	BUG_ON(id_priv->cma_dev->device != id_priv->id.device);
 
 	if (conn_param)