drm/msm/mdp4: drop mpd4_lvds_pll_init stub

drm/msm/mdp4: drop mpd4_lvds_pll_init stub

Drop the !COMMON_CLK stub for mpd4_lvds_pll_init(), the DRM_MSM driver
depends on COMMON_CLK.

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/650281/
Link: https://lore.kernel.org/r/20250425-fd-mdp4-lvds-v4-2-6b212160b44c@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>