dt-bindings: power: Add Allwinner H6/H616 PRCM PPU

The Allwinner H6 and some later SoCs contain some bits in the PRCM (Power
Reset Clock Management) block that control some power domains.
Those power domains include the one for the GPU, the PLLs and some
analogue circuits.

Signed-off-by: Andre Przywara <[e-mail]>
Reviewed-by: Rob Herring (Arm) <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Ulf Hansson <[e-mail]>

Documentation/devicetree/bindings/power/allwinner,sun50i-h6-prcm-ppu.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/power/allwinner,sun50i-h6-prcm-ppu.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Allwinner SoCs PRCM power domain controller
+
+maintainers:
+  - Andre Przywara <[e-mail]>
+
+description:
+  The Allwinner Power Reset Clock Management (PRCM) unit contains bits to
+  control a few power domains.
+
+properties:
+  compatible:
+    enum:
+      - allwinner,sun50i-h6-prcm-ppu
+      - allwinner,sun50i-h616-prcm-ppu
+      - allwinner,sun55i-a523-prcm-ppu
+
+  reg:
+    maxItems: 1
+
+  '#power-domain-cells':
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - '#power-domain-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    prcm_ppu: power-controller@7010210 {
+        compatible = "allwinner,sun50i-h616-prcm-ppu";
+        reg = <0x7010210 0x10>;
+        #power-domain-cells = <1>;
+    };