msm: kgsl: Rework GPMU initialization on startup

GPMU initialization was doing a lot of things correctly to get the
new hardware block working. It wasn't however doing them quickly and
this was costing a lot of time when waking the device up. Streamline
this process to do things quicker to save power and make the GPU
available faster.

Change-Id: Ie06995e35c89e1c60f549e3fb4b6023203c99f89
Signed-off-by: Carter Cooper <ccooper@codeaurora.org>