[media] V4L: mt9m111: fix missing return value check mt9m111_reg_clear

Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/mt9m111.c

@@ -250,7 +250,9 @@ static int mt9m111_reg_clear(struct i2c_client *client, const u16 reg,
 	int ret;
 
 	ret = mt9m111_reg_read(client, reg);
-	return mt9m111_reg_write(client, reg, ret & ~data);
+	if (ret >= 0)
+		ret = mt9m111_reg_write(client, reg, ret & ~data);
+	return ret;
 }
 
 static int mt9m111_set_context(struct mt9m111 *mt9m111,