msm: kgsl: Move context aware scaling to the scaling code

Context aware (CA) scaling is excluisvely a pwrscale concept so move all
the probing there.  This is mostly just a cut-and-paste except that the
speed_bin needs to move from Adreno to the kgsl_device so it can be
accessed from the pwrscale code.

Change-Id: Ic0dedbad54983ecf8b59b9a62991be6b4f26b242
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>