mfd: axp20x: Add support for AXP809 PMIC

The X-Powers AXP809 is a new PMIC that is paired with Allwinner's A80
SoC, along with a slave AXP806 PMIC.

This PMIC is quite similar to the earlier AXP223, though the interrupts
and regulator have changed a bit.

This patch adds support for the interrupts and power button of the PMIC.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/mfd/axp20x-rsb.c b/drivers/mfd/axp20x-rsb.c
index 28c2024..a407527 100644
--- a/drivers/mfd/axp20x-rsb.c
+++ b/drivers/mfd/axp20x-rsb.c
@@ -61,6 +61,7 @@
 
 static const struct of_device_id axp20x_rsb_of_match[] = {
 	{ .compatible = "x-powers,axp223", .data = (void *)AXP223_ID },
+	{ .compatible = "x-powers,axp809", .data = (void *)AXP809_ID },
 	{ },
 };
 MODULE_DEVICE_TABLE(of, axp20x_rsb_of_match);