msm: kgsl: Track and pass number of active context to governor

Track number of active context and pass it to governor along
with busy stats. This allows GPU DCVS to make decision based
on context count and busy stats, which helps in handling sudden
workloads.

Change-Id: I9b40e4917b30ee3f15f2c8e99669e090578f1289
Signed-off-by: Deepak Kumar <dkumar@codeaurora.org>
Signed-off-by: Divya Ponnusamy <pdivya@codeaurora.org>