dt-bindings: display/msm: Document MDSS on SA8775P

Document the MDSS hardware found on the Qualcomm SA8775P platform.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Mahadevan <quic_mahap@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/620492/
Link: https://lore.kernel.org/r/20241019-patchv3_1-v5-1-d2fb72c9a845@quicinc.com


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>