msm: kgsl: Don't consider active count if not in active state

Don't consider active_cnt variable if not already in ACTIVE state.
The active count variable does not necessarily exactly indicate the
number of open handles to GPU for switching power state. Hence,
only wait for active count to reach zero before switching to SUSPEND
state if, the current state is ACTIVE.

CRs-fixed: 483154
Change-Id: Ie025a1873cfb9237bdfba89204f4c2116549eba4
Signed-off-by: Harsh Vardhan Dwivedi <hdwivedi@codeaurora.org>