dt-bindings: display/msm: dsi-phy-7nm: Add SM8750

Add DSI PHY v7.0 for Qualcomm SM8750 SoC which is quite different from
previous (SM8650) generation.

Acked-by: Rob Herring (Arm) <[e-mail]>
Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Patchwork: https://patchwork.freedesktop.org/patch/659615/
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Dmitry Baryshkov <[e-mail]>

Documentation/devicetree/bindings/display/msm/dsi-phy-7nm.yaml

···
       - qcom,sm8450-dsi-phy-5nm
       - qcom,sm8550-dsi-phy-4nm
       - qcom,sm8650-dsi-phy-4nm
+      - qcom,sm8750-dsi-phy-3nm
 
   reg:
     items: