msm: kgsl: Fix up the legacy target register address protections

Move all of the register address protection (RAP) support for legacy
targets into the individual GPU target code. By explicitly specifying
the protected mode register instead of relying on vague generic code
we can do a better job of monitoring the list and making sure it doesn't
get accidentally changed for the worst by developers.

Change-Id: Ic0dedbad22891bb7e14722e6eb7c52ca142a7cea
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>