msm: kgsl: hold a process_private refcount in process_mem_print

There is a possible race condition where the process can be going
away while its debugfs 'mem' file is being read, which could cause
memory corruption.

CRs-Fixed: 627780
Change-Id: I697486faeb3f186fd1220d0acc1e449a4f7b77b0
Signed-off-by: Jeremy Gebben <jgebben@codeaurora.org>
msm: kgsl: Add a power constraints interface

Add an interface to hint the user specified power
constraint. User can specify a particular GPU power level
or a bandwidth vote. The power constraints are per context
or command batch. Power constraints are only for hinting
and should be used judiciously.

Change-Id: Ic10a5fff4abc88c51cd45a7d7ac58c0d4e5dcb25
Signed-off-by: Suman Tatiraju <sumant@codeaurora.org>
Signed-off-by: Lucille Sylvester <lsylvest@codeaurora.org>

Conflicts:

	drivers/gpu/msm/kgsl_device.h
	drivers/gpu/msm/kgsl_pwrscale_trustzone.c