dt-bindings: power: Convert mti,mips-cpc to DT schema

It's a Cluster Power Controller embedded into the MIPS IP cores.
Currently the corresponding dts node is supposed to have compatible
and reg properties.
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

Documentation/devicetree/bindings/power/mti,mips-cpc.txt

-Binding for MIPS Cluster Power Controller (CPC).
-
-This binding allows a system to specify where the CPC registers are
-located.
-
-Required properties:
-compatible : Should be "mti,mips-cpc".
-regs: Should describe the address & size of the CPC register region.

Documentation/devicetree/bindings/power/mti,mips-cpc.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/power/mti,mips-cpc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: MIPS Cluster Power Controller
+
+description: |
+  Defines a location of the MIPS Cluster Power Controller registers.
+
+maintainers:
+  - Paul Burton <paulburton@kernel.org>
+
+properties:
+  compatible:
+    const: mti,mips-cpc
+
+  reg:
+    description: |
+      Base address and size of an unoccupied memory region, which will be
+      used to map the MIPS CPC registers block.
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+examples:
+  - |
+    cpc@1bde0000 {
+      compatible = "mti,mips-cpc";
+      reg = <0x1bde0000 0x8000>;
+    };
+...