dt-bindings: watchdog: convert zii,rave-sp-wdt.txt to yaml format

Convert device binding doc zii,rave-sp-wdt.txt to yaml format.
Additional changes:
- Ref to watchdog.yaml.
- Remove mfd node in example.
- Remove eeprom part in example.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20241010-zii_yaml-v2-4-0ab730607422@nxp.com
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

Documentation/devicetree/bindings/watchdog/zii,rave-sp-wdt.yaml

@@ -0,0 +1,47 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/watchdog/zii,rave-sp-wdt.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Zodiac Inflight Innovations RAVE Supervisory Processor Watchdog
+
+maintainers:
+  - Frank Li <Frank.Li@nxp.com>
+
+description:
+  RAVE SP watchdog device is a "MFD cell" device corresponding to
+  watchdog functionality of RAVE Supervisory Processor. It is expected
+  that its Device Tree node is specified as a child of the node
+  corresponding to the parent RAVE SP device (as documented in
+  Documentation/devicetree/bindings/mfd/zii,rave-sp.yaml)
+
+properties:
+  compatible:
+    enum:
+      - zii,rave-sp-watchdog
+      - zii,rave-sp-watchdog-legacy
+
+  nvmem-cell-names:
+    items:
+      - const: wdt_timeout
+
+  nvmem-cells:
+    maxItems: 1
+
+required:
+  - compatible
+
+allOf:
+  - $ref: watchdog.yaml#
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    watchdog {
+        compatible = "zii,rave-sp-watchdog";
+        nvmem-cells = <&wdt_timeout>;
+        nvmem-cell-names = "wdt_timeout";
+    };
+