dt-bindings: soc: qcom: Add bindings for Qualcomm Ramp Controller

Document the Qualcomm Ramp Controller, found on various legacy
Qualcomm SoCs.

Signed-off-by: AngeloGioacchino Del Regno <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Signed-off-by: Bjorn Andersson <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

Documentation/devicetree/bindings/soc/qcom/qcom,msm8976-ramp-controller.yaml

···
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/soc/qcom/qcom,msm8976-ramp-controller.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm Ramp Controller
+
+maintainers:
+  - AngeloGioacchino Del Regno <[e-mail]>
+
+description:
+  The Ramp Controller is used to program the sequence ID for pulse
+  swallowing, enable sequences and link Sequence IDs (SIDs) for the
+  CPU cores on some Qualcomm SoCs.
+
+properties:
+  compatible:
+    enum:
+      - qcom,msm8976-ramp-controller
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    cpu-power-controller@b014000 {
+        compatible = "qcom,msm8976-ramp-controller";
+        reg = <0x0b014000 0x68>;
+    };