msm: kgsl: Reassign always on register offset when no GMU

On A6XX, if the GMU is not enabled or not present, use the CP always
on register offset rather than the GMU always on register offset.

Change-Id: Ibb5d096e2b6e5f073d3b28628cb57d010a3d668b
Signed-off-by: Carter Cooper <ccooper@codeaurora.org>