msm: sde: replace rsc with power domain for rotator

Replace rsc with power domain so rotator power can
be controlled by power domain provider, if enabled;
otherwise, rotator will request regulator directly.

Change-Id: I4668227b37d585e55e2be0eb75f377a9e8cc0356
Signed-off-by: Alan Kwong <akwong@codeaurora.org>