msm: kgsl: Finish up the last bits of the perfcounter transition

Now that all the perfcounter code is safely target specific finish up the
transition. First move the perfcounter definition from the gpudev to the
adreno_gpu_core so that we can specify the list per target which gives us
more control than modifying the gpudev at runtime or creating multiple
gpudev structs just for the perfcounter deltas.

Further drive home the point by marking the perfcounter and groups
as const. The perfcounter migration has now completed. You don't have
to go home, but you can't stay here.

Change-Id: Ic0dedbad4b4dbb8e9e49ed94dc23b97fc578324b
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>