drm/msm/shd: add cont_splash support for shared display

Add checking for base crtc complete in case if continuous splash is
enabled. Also add suspend/resume support for shared display when
command is directly set from kernel.

Change-Id: I51954ed7dff84828e34316790eac4829ca5041c2
Signed-off-by: Xiaowen Wu <wxiaowen@codeaurora.org>