drm/msm/dpu: move dpu_encoder_helper_phys_setup_cdm to dpu_encoder

drm/msm/dpu: move dpu_encoder_helper_phys_setup_cdm to dpu_encoder

Move dpu_encoder_helper_phys_setup_cdm to dpu_encoder in preparation for
implementing YUV420 over DP, which requires CDM compatibility.

Changes in v2:
	- Slightly change the wording of the commit text to make clear
	  that YUV over DP requires CDM

Signed-off-by: Paloma Arellano <quic_parellan@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/579611/
Link: https://lore.kernel.org/r/20240222194025.25329-6-quic_parellan@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>