msm: kgsl: Clear out unneeded register address protection code

Now that the register address protection (RAP) support has been
moved out of the generic code get rid of a few bits and pieces
of generic support that we no longer need.

Change-Id: Ic0dedbad3d507029244ba98ba1124deb980e990c
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>