msm: sde: Add pre/post power event handler in SDE rotator

For pre power off event, we want to check for rotator IDLE status and
generate a timeout event logging if the rotator is still in BUSY state.

For post power on event, rotator is reset to default HW state. It is
necessary to synchronize the SW timestamp with the HW register location.

CRs-Fixed: 1066270
Change-Id: I1041141b8dc80db0baec7ffe71a5c2a7b41e2cbb
Signed-off-by: Benjamin Chan <bkchan@codeaurora.org>