dt-bindings: display/msm/gmu: Add Adreno 840 GMU

Document Adreno 840 GMU in the dt-binding specification.

Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Akhil P Oommen <akhilpo@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/689031/
Message-ID: <20251118-kaana-gpu-support-v4-20-86eeb8e93fb6@oss.qualcomm.com>
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>

Documentation/devicetree/bindings/display/msm/gmu.yaml

@@ -21,7 +21,7 @@ properties:
   compatible:
     oneOf:
       - items:
-          - pattern: '^qcom,adreno-gmu-[67][0-9][0-9]\.[0-9]$'
+          - pattern: '^qcom,adreno-gmu-[6-8][0-9][0-9]\.[0-9]$'
           - const: qcom,adreno-gmu
       - items:
           - pattern: '^qcom,adreno-gmu-x[1-9][0-9][0-9]\.[0-9]$'
@@ -299,6 +299,34 @@ allOf:
       required:
         - qcom,qmp
 
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: qcom,adreno-gmu-840.1
+    then:
+      properties:
+        reg:
+          items:
+            - description: Core GMU registers
+        reg-names:
+          items:
+            - const: gmu
+        clocks:
+          items:
+            - description: GPU AHB clock
+            - description: GMU clock
+            - description: GPU CX clock
+            - description: GPU MEMNOC clock
+            - description: GMU HUB clock
+        clock-names:
+          items:
+            - const: ahb
+            - const: gmu
+            - const: cxo
+            - const: memnoc
+            - const: hub
+
   - if:
       properties:
         compatible: