drm/msm/sde: add mode change request to cdm resource update

CDM is used by writeback for luma/chroma output. CDM resource
request is detected in atomic check; however, no explicit crtc
mode change is currently registered; hence, CDM request is not
honoured if there is no other accompanying mode change.

Add explicit crtc mode change request to existing CDM request so
CDM request is processed during encoder mode set.

Change-Id: Ib2518c91d348b0fd00e9ca82cfeaeb1eaa4bf6c3
Signed-off-by: Alan Kwong <akwong@codeaurora.org>