msm: kgsl: Trigger preemption only if GMU is in ACTIVE state

Wait for GMU to move to ACTIVE state before triggering preemption.
This is required to make sure CP doesn't interrupt GMU during
wake-up from IFPC.

Change-Id: I9c8ee07a4887deb30483b5523585d547b5d38806
Signed-off-by: Deepak Kumar <dkumar@codeaurora.org>