iio: light: add missing vcnl4040 of_compatible

Commit 5a441aade5 ("iio: light: vcnl4000 add support for the VCNL4040
proximity and light sensor") added the support for the vcnl4040 but
forgot to add the of_compatible. Fix this by adding it now.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Fixes: 5a441aade5 ("iio: light: vcnl4000 add support for the VCNL4040 proximity and light sensor")
Reviewed-by: Angus Ainslie (Purism) angus@akkea.ca
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/light/vcnl4000.c

@@ -408,6 +408,10 @@ static const struct of_device_id vcnl_4000_of_match[] = {
 		.compatible = "vishay,vcnl4020",
 		.data = (void *)VCNL4010,
 	},
+	{
+		.compatible = "vishay,vcnl4040",
+		.data = (void *)VCNL4040,
+	},
 	{
 		.compatible = "vishay,vcnl4200",
 		.data = (void *)VCNL4200,