msm: kgsl: Idle GPU core before programming SMMU from CPU

Always idle the GPU core before programming SMMU from CPU for
SMMU-v1. GPU core was already being idled before programming
the pagetable register, make sure that it's also idle before
programming the tlb invalidate registers. This is required to
prevent a deadlock from happening at the bus level.

Change-Id: Ie901b92028b289fc546ab6186eedd01411d0727e
Signed-off-by: Shubhraprakash Das <sadas@codeaurora.org>
Signed-off-by: Tarun Karra <tkarra@codeaurora.org>