mfd: axp20x: Add AXP22x regulator information to DT bindings

Add the list of regulators for AXP22x to the DT bindings.
This includes the names and supply names.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

Documentation/devicetree/bindings/mfd/axp20x.txt

@@ -49,6 +49,31 @@ LDO3		: LDO		: ldo3in-supply
 LDO4		: LDO		: ldo24in-supply	: shared supply
 LDO5		: LDO		: ldo5in-supply
 
+AXP221 regulators, type, and corresponding input supply names:
+
+Regulator	  Type		  Supply Name		  Notes
+---------	  ----		  -----------		  -----
+DCDC1		: DC-DC buck	: vin1-supply
+DCDC2		: DC-DC buck	: vin2-supply
+DCDC3		: DC-DC	buck	: vin3-supply
+DCDC4		: DC-DC	buck	: vin4-supply
+DCDC5		: DC-DC	buck	: vin5-supply
+DC1SW		: On/Off Switch	: dcdc1-supply		: DCDC1 secondary output
+DC5LDO		: LDO		: dcdc5-supply		: input from DCDC5
+ALDO1		: LDO		: aldoin-supply		: shared supply
+ALDO2		: LDO		: aldoin-supply		: shared supply
+ALDO3		: LDO		: aldoin-supply		: shared supply
+DLDO1		: LDO		: dldoin-supply		: shared supply
+DLDO2		: LDO		: dldoin-supply		: shared supply
+DLDO3		: LDO		: dldoin-supply		: shared supply
+DLDO4		: LDO		: dldoin-supply		: shared supply
+ELDO1		: LDO		: eldoin-supply		: shared supply
+ELDO2		: LDO		: eldoin-supply		: shared supply
+ELDO3		: LDO		: eldoin-supply		: shared supply
+LDO_IO0		: LDO		: ips-supply		: GPIO 0
+LDO_IO1		: LDO		: ips-supply		: GPIO 1
+RTC_LDO		: LDO		: ips-supply		: always on
+
 Example:
 
 axp209: pmic@34 {