[media] media:dvb:fix up ENOIOCTLCMD error handling

At commit 07d106d0, Linus pointed out that ENOIOCTLCMD should be
translated as ENOTTY to user mode.
Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb-core/dvbdev.c

@@ -420,7 +420,7 @@ int dvb_usercopy(struct file *file,
 	/* call driver */
 	mutex_lock(&dvbdev_mutex);
 	if ((err = func(file, cmd, parg)) == -ENOIOCTLCMD)
-		err = -EINVAL;
+		err = -ENOTTY;
 	mutex_unlock(&dvbdev_mutex);
 
 	if (err < 0)