Drop the assigned clock rate property and vote on the mdp clock as per
calculated value during the usecase.

This patch is dependent on the patch ("drm/msm/disp/dpu1: set mdp clk
to the maximum frequency in opp table during probe") [1].

[1] https://lore.kernel.org/r/1647269217-14064-2-git-send-email-quic_vpolimer@quicinc.com/Signed-off-by: Vinod Polimera <quic_vpolimer@quicinc.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/1647919631-14447-3-git-send-email-quic_vpolimer@quicinc.com