drm/msm/dp: Remove pixel_rate from struct dp_ctrl

This struct member is stored to in the function that calls the function
which uses it. That's possible with a function argument instead of
storing to a struct member. Pass the pixel_rate as an argument instead
to simplify the code. Note that dp_ctrl_link_maintenance() was storing
the pixel_rate but never using it so we just remove the assignment from
there.

Cc: Kuogee Hsieh <quic_khsieh@quicinc.com>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/490772/
Link: https://lore.kernel.org/r/20220623002540.871994-3-swboyd@chromium.org


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>