drm/msm/sde: add power_enable before cleanup of unused planes

Unused pipes are halted at the end of the commit in the cleanup.
During this if the clocks are turned off will lead to NOC error.
This change adds the power enable before unused plane halt to make
sure the clocks are on at the time of halting.

Change-Id: I162b001651516926464ba386c82d94275a0a2bc5
Signed-off-by: Harsh Sahu <hsahu@codeaurora.org>