regulator: vqmmc-ipq4019-regulator: add binding document

This patch adds bindings for the Qualcomm IPQ4019 VQMMC SD LDO driver.
Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Message-Id: <20200122134023.1467806-1-robert.marko@sartura.hr>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/vqmmc-ipq4019-regulator.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/regulator/vqmmc-ipq4019-regulator.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm IPQ4019 VQMMC SD LDO regulator
+
+maintainers:
+  - Robert Marko <robert.marko@sartura.hr>
+
+description: |
+  Qualcomm IPQ4019 SoC-s feature a built a build SD/EMMC controller,
+  in order to support both 1.8 and 3V I/O voltage levels an LDO
+  controller is also embedded.
+
+allOf:
+  - $ref: "regulator.yaml#"
+
+properties:
+  compatible:
+    const: qcom,vqmmc-ipq4019-regulator
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+examples:
+  - |
+    regulator@1948000 {
+      compatible = "qcom,vqmmc-ipq4019-regulator";
+      reg = <0x01948000 0x4>;
+      regulator-name = "vqmmc";
+      regulator-min-microvolt = <1500000>;
+      regulator-max-microvolt = <3000000>;
+      regulator-always-on;
+      status = "disabled";
+    };
+...