IB/core: Use rdma_ah_attr accessor functions

Modify core and driver components to use accessor functions
introduced to access individual fields of rdma_ah_attr

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Don Hiatt <don.hiatt@intel.com>
Reviewed-by: Sean Hefty <sean.hefty@intel.com>
Reviewed-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Signed-off-by: Dasaratharaman Chandramouli <dasaratharaman.chandramouli@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 34dc81d..f3b800f 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -929,7 +929,8 @@ static int cma_modify_qp_rtr(struct rdma_id_private *id_priv,
 		goto out;
 
 	ret = ib_query_gid(id_priv->id.device, id_priv->id.port_num,
-			   qp_attr.ah_attr.grh.sgid_index, &sgid, NULL);
+			   rdma_ah_read_grh(&qp_attr.ah_attr)->sgid_index,
+			   &sgid, NULL);
 	if (ret)
 		goto out;