media: ov7740: remove an unused var

Fix this warning regression:
   drivers/media/i2c/ov7740.c: warning: variable 'ret' set but not used [-Wunused-but-set-variable]:  => 276:6
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/i2c/ov7740.c

@@ -279,7 +279,7 @@ static int ov7740_get_register(struct v4l2_subdev *sd,
 	reg->val = val;
 	reg->size = 1;
 
-	return 0;
+	return ret;
 }
 
 static int ov7740_set_register(struct v4l2_subdev *sd,