dt-bindings: display/msm: gpu: add rbcpr clock

Describe the RBCPR clock used on msm8996 (A530), MSM8998 (A540) and
SDM630/660 (A508/A512).
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/517470/
Link: https://lore.kernel.org/r/20230109054407.330839-1-dmitry.baryshkov@linaro.orgSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

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

@@ -149,6 +149,8 @@ allOf:
                 description: GPU 3D engine clock
               - const: rbbmtimer
                 description: GPU RBBM Timer for Adreno 5xx series
+              - const: rbcpr
+                description: GPU RB Core Power Reduction clock
           minItems: 2
           maxItems: 7