msm: kgsl: Enable APRIV control for targets that support it

A650 and A620 have a new feature that allows us to mark certain memory
transactions in the CP to use apriv by default which allows us to mark
most CP used memory as privileged without explicitly turning the bit on and
off.

As a bonus the privilege level extends to register address protection too
so we can go about our business without setting APRIV or using the
CP_SET_PROTECTED_MODE opcode in the ringbuffer for those targets lucky
enough to have this feature.

Change-Id: Ic0dedbadec4c9b9147a0fbec17e1c92200ebd066
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>