disp: msm: remove runtime_pm support from rsc driver

Remove runtime_pm support from rsc driver. RSC driver
does not vote for MMCX. It relies on sde core driver
to keep vote and trigger call. That brings additional
dependency to manage runtime_pm references during
pm_suspend/pm_resume call. This change also updates
the runtime_pm call to manage the pm_suspend in
msm drm driver.

Change-Id: I111771994822c82db53fb6c23e5d942f90fd1af2
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>