dt-bindings: power: supply: Add DT bindings for max77650

Add the DT binding document for the battery charger module of max77650.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

Documentation/devicetree/bindings/power/supply/max77650-charger.txt

+Battery charger driver for MAX77650 PMIC from Maxim Integrated.
+
+This module is part of the MAX77650 MFD device. For more details
+see Documentation/devicetree/bindings/mfd/max77650.txt.
+
+The charger is represented as a sub-node of the PMIC node on the device tree.
+
+Required properties:
+--------------------
+- compatible:		Must be "maxim,max77650-charger"
+
+Optional properties:
+--------------------
+- input-voltage-min-microvolt:	Minimum CHGIN regulation voltage. Must be one
+				of: 4000000, 4100000, 4200000, 4300000,
+				4400000, 4500000, 4600000, 4700000.
+- input-current-limit-microamp:	CHGIN input current limit (in microamps). Must
+				be one of: 95000, 190000, 285000, 380000,
+				475000.
+
+Example:
+--------
+
+	charger {
+		compatible = "maxim,max77650-charger";
+		input-voltage-min-microvolt = <4200000>;
+		input-current-limit-microamp = <285000>;
+	};