dt-bindings: gpu: img,powervr-rogue: Add TH1520 GPU support

Rework the PowerVR Rogue GPU binding to use an explicit, per variant
style for defining power domain properties and add support for the
T-HEAD TH1520 SoC's GPU.

To improve clarity and precision, the binding is refactored so that
power domain items are listed explicitly for each variant [1]. The
previous method relied on an implicit, positional mapping between the
`power-domains` and `power-domain-names` properties. This change
replaces the generic rules with self contained if/then blocks for each
GPU variant, making the relationship between power domains and their
names explicit and unambiguous.

The generic if block for img,img-rogue, which previously required
power-domains and power-domain-names for all variants, is removed.
Instead, each specific GPU variant now defines its own power domain
requirements within a self-contained if/then block, making the schema
more explicit.

This new structure is then used to add support for the
`thead,th1520-gpu`. While its BXM-4-64 IP has two conceptual power
domains, the TH1520 SoC integrates them behind a single power gate. The
new binding models this with a specific rule that enforces a single
`power-domains` entry and disallows the `power-domain-names` property.

Link: https://lore.kernel.org/all/4d79c8dd-c5fb-442c-ac65-37e7176b0cdd@linaro.org/ [1]

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Matt Coster <matt.coster@imgtec.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
Link: https://lore.kernel.org/r/20250822-apr_14_for_sending-v13-2-af656f7cc6c3@samsung.com
Signed-off-by: Matt Coster <matt.coster@imgtec.com>

Documentation/devicetree/bindings/gpu/img,powervr-rogue.yaml

@@ -21,6 +21,11 @@ properties:
           # work with newer dts.
           - const: img,img-axe
           - const: img,img-rogue
+      - items:
+          - enum:
+              - thead,th1520-gpu
+          - const: img,img-bxm-4-64
+          - const: img,img-rogue
       - items:
           - enum:
               - ti,j721s2-gpu
@@ -77,18 +82,6 @@ required:
 additionalProperties: false
 
 allOf:
-  # Constraints added alongside the new compatible strings that would otherwise
-  # create an ABI break.
-  - if:
-      properties:
-        compatible:
-          contains:
-            const: img,img-rogue
-    then:
-      required:
-        - power-domains
-        - power-domain-names
-
   - if:
       properties:
         compatible:
@@ -97,9 +90,32 @@ allOf:
     then:
       properties:
         power-domains:
-          maxItems: 1
+          items:
+            - description: Power domain A
         power-domain-names:
           maxItems: 1
+      required:
+        - power-domains
+        - power-domain-names
+
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: thead,th1520-gpu
+    then:
+      properties:
+        clocks:
+          minItems: 3
+        clock-names:
+          minItems: 3
+        power-domains:
+          items:
+            - description: The single, unified power domain for the GPU on the
+                TH1520 SoC, integrating all internal IP power domains.
+        power-domain-names: false
+      required:
+        - power-domains
 
   - if:
       properties:
@@ -109,9 +125,14 @@ allOf:
     then:
       properties:
         power-domains:
-          minItems: 2
+          items:
+            - description: Power domain A
+            - description: Power domain B
         power-domain-names:
           minItems: 2
+      required:
+        - power-domains
+        - power-domain-names
 
   - if:
       properties: