media: dmxdev: fix error code for invalid ioctls

BugLink: https://bugs.launchpad.net/bugs/1775771

[ Upstream commit a145f64c ]

Returning -EINVAL when an ioctl is not implemented is a very
bad idea, as it is hard to distinguish from other error
contitions that an ioctl could lead. Replace it by its
right error code: -ENOTTY.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/media/dvb-core/dmxdev.c

@@ -1071,7 +1071,7 @@ static int dvb_demux_do_ioctl(struct file *file,
 		break;
 
 	default:
-		ret = -EINVAL;
+		ret = -ENOTTY;
 		break;
 	}
 	mutex_unlock(&dmxdev->mutex);