regulator: Add labibb regulator binding

Adding the devicetree binding for labibb regulator.

 [sumits: cleanup as per review comments and update to yaml]
Signed-off-by: Nisha Kumari <nishakumari@codeaurora.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200622124110.20971-3-sumit.semwal@linaro.orgSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/qcom-labibb-regulator.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/regulator/qcom-labibb-regulator.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm's LAB(LCD AMOLED Boost)/IBB(Inverting Buck Boost) Regulator
+
+maintainers:
+  - Sumit Semwal <sumit.semwal@linaro.org>
+
+description:
+  LAB can be used as a positive boost power supply and IBB can be used as a
+  negative boost power supply for display panels. Currently implemented for
+  pmi8998.
+
+properties:
+  compatible:
+    const: qcom,pmi8998-lab-ibb
+
+  lab:
+    type: object
+
+    properties:
+
+      interrupts:
+        maxItems: 1
+        description:
+          Short-circuit interrupt for lab.
+
+    required:
+    - interrupts
+
+  ibb:
+    type: object
+
+    properties:
+
+      interrupts:
+        maxItems: 1
+        description:
+          Short-circuit interrupt for lab.
+
+    required:
+    - interrupts
+
+required:
+  - compatible
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    labibb {
+      compatible = "qcom,pmi8998-lab-ibb";
+
+      lab {
+        interrupts = <0x3 0x0 IRQ_TYPE_EDGE_RISING>;
+        interrupt-names = "sc-err";
+      };
+
+      ibb {
+        interrupts = <0x3 0x2 IRQ_TYPE_EDGE_RISING>;
+        interrupt-names = "sc-err";
+      };
+    };
+
+...