rtc: rx8581: Add OF device ID table

The driver doesn't have a struct of_device_id table but supported devices
are registered via Device Trees. This is working on the assumption that a
I2C device registered via OF will always match a legacy I2C device ID and
that the MODALIAS reported will always be of the form i2c:<device>.

But this could change in the future so the correct approach is to have an
OF device ID table if the devices are registered via OF.
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/rtc-rx8581.c

@@ -308,9 +308,16 @@ static const struct i2c_device_id rx8581_id[] = {
 };
 MODULE_DEVICE_TABLE(i2c, rx8581_id);
 
+static const struct of_device_id rx8581_of_match[] = {
+	{ .compatible = "epson,rx8581" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, rx8581_of_match);
+
 static struct i2c_driver rx8581_driver = {
 	.driver		= {
 		.name	= "rtc-rx8581",
+		.of_match_table = of_match_ptr(rx8581_of_match),
 	},
 	.probe		= rx8581_probe,
 	.id_table	= rx8581_id,