scsi: ibmvscsis: Fix write_pending failure path

For write_pending if the queue is down or client failed then return -EIO
so that LIO can properly process the completed command. Prior we
returned 0 since LIO could not handle it properly. Now with commit
fa7e25cf ("target: Fix unknown fabric callback queue-full errors")
that patch addresses LIO's ability to handle things right.
Signed-off-by: NBryant G. Ly <bgly@us.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c

@@ -3767,7 +3767,7 @@ static int ibmvscsis_write_pending(struct se_cmd *se_cmd)
 	 */
 	if ((vscsi->flags & (CLIENT_FAILED | RESPONSE_Q_DOWN))) {
 		pr_err("write_pending failed since: %d\n", vscsi->flags);
-		return 0;
+		return -EIO;
 	}
 
 	rc = srp_transfer_data(cmd, &vio_iu(iue)->srp.cmd, ibmvscsis_rdma,