drm/msm/dpu: modify timing engine programming for YUV420 over DP

Adjust the encoder timing engine setup programming in the case of video
mode for YUV420 over DP to accommodate CDM.

Changes in v3:
	- Move drm_display_mode's hskew division to another patch
	- Minor cleanup

Changes in v2:
	- Move timing engine programming to this patch

Signed-off-by: Paloma Arellano <quic_parellan@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/579634/
Link: https://lore.kernel.org/r/20240222194025.25329-18-quic_parellan@quicinc.com


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