s390/dasd: fix ioctl return value

For unimplemented ioctls the dasd driver should return -ENOTTY.

Reported-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Acked-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c
index 40a826a..2fb2b9e 100644
--- a/drivers/s390/block/dasd_eckd.c
+++ b/drivers/s390/block/dasd_eckd.c
@@ -3804,7 +3804,7 @@
 	case BIODASDSYMMIO:
 		return dasd_symm_io(device, argp);
 	default:
-		return -ENOIOCTLCMD;
+		return -ENOTTY;
 	}
 }