dt-bindings: dsi-controller-main: Document missing msm8976 compatible

When all dsi-ctrl compats were added msm8976 was missed, include it too.
Signed-off-by: Adam Skladowski <a39.skl@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/575288/
Link: https://lore.kernel.org/r/20240121194221.13513-3-a39.skl@gmail.comSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Documentation/devicetree/bindings/display/msm/dsi-controller-main.yaml

@@ -19,6 +19,7 @@ properties:
               - qcom,msm8916-dsi-ctrl
               - qcom,msm8953-dsi-ctrl
               - qcom,msm8974-dsi-ctrl
+              - qcom,msm8976-dsi-ctrl
               - qcom,msm8996-dsi-ctrl
               - qcom,msm8998-dsi-ctrl
               - qcom,qcm2290-dsi-ctrl
@@ -248,6 +249,7 @@ allOf:
           contains:
             enum:
               - qcom,msm8953-dsi-ctrl
+              - qcom,msm8976-dsi-ctrl
     then:
       properties:
         clocks: