IB/mthca: Allow the QP state transition RESET->RESET

RESET->RESET is an allowed QP state transition, so mthca should handle
it correctly, by just returning success without involving the firmware.

Signed-off-by: Dotan Barak <dotanb@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/mthca/mthca_qp.c

@@ -573,6 +573,11 @@ int mthca_modify_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr, int attr_mask,
 		goto out;
 	}
 
+	if (cur_state == new_state && cur_state == IB_QPS_RESET) {
+		err = 0;
+		goto out;
+	}
+
 	if ((attr_mask & IB_QP_PKEY_INDEX) &&
 	     attr->pkey_index >= dev->limits.pkey_table_len) {
 		mthca_dbg(dev, "P_Key index (%u) too large. max is %d\n",