IB/ehca: Require in_wc in process_mad()

If the caller does not pass a valid in_wc to process_mad(), return MAD
failure status, as it is not possible to generate a valid MAD redirect
response (and redirects are the only MAD responses ehca generates).
Signed-off-by: Alexander Schmidt <alexs@linux.vnet.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/ehca/ehca_sqp.c

@@ -222,7 +222,7 @@ int ehca_process_mad(struct ib_device *ibdev, int mad_flags, u8 port_num,
 {
 	int ret;
 
-	if (!port_num || port_num > ibdev->phys_port_cnt)
+	if (!port_num || port_num > ibdev->phys_port_cnt || !in_wc)
 		return IB_MAD_RESULT_FAILURE;
 
 	/* accept only pma request */