dt-bindings: regulator: add document bindings for slg51000

Add device tree binding information for slg51000 regulator driver.
Example bindings for SLG51000 are added.
Signed-off-by: Eric Jeong <eric.jeong.opensource@diasemi.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/slg51000.txt

+* Dialog Semiconductor SLG51000 Voltage Regulator
+
+Required properties:
+- compatible : Should be "dlg,slg51000" for SLG51000
+- reg : Specifies the I2C slave address.
+- xxx-supply: Input voltage supply regulator for ldo3 to ldo7.
+  These entries are required if regulators are enabled for a device.
+  An absence of these properties can cause the regulator registration to fail.
+  If some of input supply is powered through battery or always-on supply then
+  also it is required to have these parameters with proper node handle of always
+  on power supply.
+    vin3-supply: Input supply for ldo3
+    vin4-supply: Input supply for ldo4
+    vin5-supply: Input supply for ldo5
+    vin6-supply: Input supply for ldo6
+    vin7-supply: Input supply for ldo7
+
+Optional properties:
+- interrupt-parent : Specifies the reference to the interrupt controller.
+- interrupts : IRQ line information.
+- dlg,cs-gpios : Specify a valid GPIO for chip select
+
+Sub-nodes:
+- regulators : This node defines the settings for the regulators.
+  The content of the sub-node is defined by the standard binding
+  for regulators; see regulator.txt.
+
+  The SLG51000 regulators are bound using their names listed below:
+    ldo1
+    ldo2
+    ldo3
+    ldo4
+    ldo5
+    ldo6
+    ldo7
+
+Optional properties for regulators:
+- enable-gpios : Specify a valid GPIO for platform control of the regulator.
+
+Example:
+	pmic: slg51000@75 {
+		compatible = "dlg,slg51000";
+		reg = <0x75>;
+
+		regulators {
+			ldo1 {
+			        regulator-name = "ldo1";
+			        regulator-min-microvolt = <2400000>;
+			        regulator-max-microvolt = <3300000>;
+			};
+
+			ldo2 {
+			        regulator-name = "ldo2";
+			        regulator-min-microvolt = <2400000>;
+			        regulator-max-microvolt = <3300000>;
+			};
+
+			ldo3 {
+			        regulator-name = "ldo3";
+			        regulator-min-microvolt = <1200000>;
+			        regulator-max-microvolt = <3750000>;
+			};
+
+			ldo4 {
+			        regulator-name = "ldo4";
+			        regulator-min-microvolt = <1200000>;
+			        regulator-max-microvolt = <3750000>;
+			};
+
+			ldo5 {
+			        regulator-name = "ldo5";
+			        regulator-min-microvolt = <500000>;
+			        regulator-max-microvolt = <1200000>;
+			};
+
+			ldo6 {
+			        regulator-name = "ldo6";
+			        regulator-min-microvolt = <500000>;
+			        regulator-max-microvolt = <1200000>;
+			};
+
+			ldo7 {
+			        regulator-name = "ldo7";
+			        regulator-min-microvolt = <1200000>;
+			        regulator-max-microvolt = <3750000>;
+			};
+		};
+	};