msm: kgsl: Support voting for CPU to GPU config path

Keeping a bus vote for CPU to GPU config path will make
sure that the required clocks are ON during the CPU
access. Keep a higher vote during wakeup to improve
GPU wakeup latency, keep higher vote during snapshot
also to improve register access latency. Keeping lower
vote after wakeup is good enough to make sure it is
running at minimum possible clock and voltage corner.

Change-Id: I9c9c86be6fff487874c94073b26fc2beb2063687
Signed-off-by: Prakash Kamliya <pkamliya@codeaurora.org>