msm: kgsl: Do GPU bus governor management

Currently, bus governor operations like devfreq update, suspend & resume
are done by the adreno_tz governor. Instead of that, do these bus governor
operations from the driver.

Change-Id: I13bf2405f05668346cbe0519a3d143addf75653f
Signed-off-by: Akhil P Oommen <akhilpo@codeaurora.org>