mfd: qcom,tcsr: Add device tree binding for TCSR

This patch adds the device tree binding for the Qualcomm Top Control and
Status Register device.  The TCSR is comprised of a set of registers that
provide various control and status functions for attached peripherals.
Signed-off-by: Andy Gross <agross@codeaurora.org>
Signed-off-by: Kumar Gala <galak@codeaurora.org>
Signed-off-by: Olof Johansson <olof@lixom.net>

Documentation/devicetree/bindings/mfd/qcom,tcsr.txt

+QCOM Top Control and Status Register
+
+Qualcomm devices have a set of registers that provide various control and status
+functions for their peripherals.  This node is intended to allow access to these
+registers via syscon.
+
+Required properties:
+- compatible:	Should contain:
+		"qcom,tcsr-ipq8064", "syscon" for IPQ8064
+		"qcom,tcsr-apq8064", "syscon" for APQ8064
+		"qcom,tcsr-msm8660", "syscon" for MSM8660
+		"qcom,tcsr-msm8960", "syscon" for MSM8960
+		"qcom,tcsr-msm8974", "syscon" for MSM8974
+		"qcom,tcsr-apq8084", "syscon" for APQ8084
+		"qcom,tcsr-msm8916", "syscon" for MSM8916
+- reg: Address range for TCSR registers
+
+Example:
+	tcsr: syscon@1a400000 {
+		compatible = "qcom,tcsr-msm8960", "syscon";
+		reg = <0x1a400000 0x100>;
+	};