drm/msm/sde: add idle power collapse support for cmd mode panels

Add idle power collapse support with the help of resource
controller to control the encoder states between ON, OFF and IDLE
for cmd mode panels. The device is put to IDLE state, when there are
no frame updates for 4 vsyncs. MDP core clocks and GDSC are
enabled during kickoff and a delayed work scheduled after the
FRAME_DONE event would turn off the resources, if there are no
updates for 4 vsyncs. During the IDLE state though the resources
are turned off, the panel is still left on, which would be
refreshing from its internal memory.

Change-Id: I8d6367173092715c2c31b67a699dc3a4e5acfbc6
Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>