dt-bindings: rockchip: grf: Narrow allowed reboot modes

syscon-reboot-mode schema allows arbitrary "mode-.* properties but only
a subset actually makes sense and is valid.  Provide negative look-ahead
pattern to disallow any modes not supported by the device, which
tightens the binding.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20260701105849.197086-4-krzysztof.kozlowski@oss.qualcomm.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

Documentation/devicetree/bindings/soc/rockchip/grf.yaml

@@ -239,11 +239,14 @@ allOf:
       properties:
         reboot-mode:
           type: object
-
           $ref: /schemas/power/reset/syscon-reboot-mode.yaml#
-
           unevaluatedProperties: false
 
+          patternProperties:
+            # Negative look-ahead to disallow unsupported modes. The '$' has to be
+            # part of lookahead group to work, instead of trailing outside of ().
+            "^mode-(?!(bootloader$|fastboot$|loader$|normal$|recovery$))": false
+
   - if:
       properties:
         compatible: