dt-bindings: power: supply: olpc-battery: Convert to DT schema format

Convert the binding to DT schema format.
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/power/supply/olpc-battery.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/power/supply/olpc-battery.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: OLPC Battery
+
+maintainers:
+  - Sebastian Reichel <sre@kernel.org>
+
+allOf:
+  - $ref: power-supply.yaml#
+
+properties:
+  compatible:
+    oneOf:
+      - items:
+          - const: olpc,xo1.5-battery
+          - const: olpc,xo1-battery
+      - items:
+          - const: olpc,xo1-battery
+
+required:
+  - compatible
+
+additionalProperties: false

Documentation/devicetree/bindings/power/supply/olpc_battery.txt

-OLPC battery
-~~~~~~~~~~~~
-
-Required properties:
-  - compatible : "olpc,xo1-battery" or "olpc,xo1.5-battery"