sunxi: power: axp818: Add support for switch SW

The AXP818 has a switchable output, SW. This is commonly used for
controlling power to the LCD backlight.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
index b365fd4..02cb8e7 100644
--- a/drivers/power/Kconfig
+++ b/drivers/power/Kconfig
@@ -265,6 +265,13 @@
 	Set the voltage (mV) to program the axp pmic fldo3 at, set to 0 to
 	disable fldo3.
 
+config AXP_SW_ON
+	bool "axp pmic sw on"
+	depends on AXP818_POWER
+	default n
+	---help---
+	Enable to turn on axp pmic sw.
+
 config SY8106A_VOUT1_VOLT
 	int "SY8106A pmic VOUT1 voltage"
 	depends on SY8106A_POWER