[media] v4l2-ioctl: allow all controls if ctrl_class == 0

The check_ext_ctrls() function in v4l2-ioctl.c checks if all controls in the
control array are from the same control class as c->ctrl_class. However,
that check should only be done if c->ctrl_class != 0. A 0 value means
that this restriction does not apply.

So return 1 (OK) if c->ctrl_class == 0.

Found by running v4l2-compliance on the uvc driver.
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Acked-by: NSakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/v4l2-core/v4l2-ioctl.c

@@ -901,6 +901,8 @@ static int check_ext_ctrls(struct v4l2_ext_controls *c, int allow_priv)
 	 */
 	if (!allow_priv && c->ctrl_class == V4L2_CID_PRIVATE_BASE)
 		return 0;
+	if (c->ctrl_class == 0)
+		return 1;
 	/* Check that all controls are from the same control class. */
 	for (i = 0; i < c->count; i++) {
 		if (V4L2_CTRL_ID2CLASS(c->controls[i].id) != c->ctrl_class) {