msm: kgsl: Add a sync event to map GMU events to ftrace timeline

GMU events will be streamed to the host if GMU log streaming is
enabled. Being able to view GMU events on the same timeline
as GPU and host events is helpful for profiling. Add a sync event
to map GMU AO counter ticks to the ftrace timeline just before
bringing the GMU out of reset.

Change-Id: I7e2696f4d0d8666a2fcdfccb358619277e5949b8
Signed-off-by: Sushmita Susheelendra <ssusheel@codeaurora.org>