dt-bindings: interrupt-controller: mediatek,mt6577-sysirq: Drop invalid JSON pointer

The $ref "arm,gic.yaml#/properties/#interrupt-cells" doesn't work when used with another json-schema implementation (rust). The issue is it not a valid URI due to the 2nd "#" character in the JSON pointer. Though a "#" is supposed to be valid within a JSON pointer. A possible solution is to encode the "#" as "%23" instead, but the dtschema tools don't handle that.

Just avoid all these issues as the $ref only resolves to a "const: 3" schema and specify it directly.

---
 .../bindings/interrupt-controller/mediatek,mt6577-sysirq.yaml  | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

index 30d76692ca87..b94fc3cec175 100644
@@ -49,7 +49,8 @@ properties:
   interrupt-controller: true
 
   "#interrupt-cells":
-    $ref: arm,gic.yaml#/properties/#interrupt-cells
+    const: 3
+    description: The cells have the same encoding as defined in arm,gic.yaml.
 
 required:
   - reg

2.53.0