msm: kgsl: Fix some questionable pointer math in the profile code

Commit 4f40ffa1 passes a pointer to
a pointer to the ringbuffer memory to adreno_profile_preib_processing
and adreno_profile_postib_processing and expects those functions to
dereference the pointer and write to it.  Unfortunately, the pointer
math attempted to be more clever than the compiler and lost resulting
in a kernel panic when this code is run.

Explicitly dereference the pointer use it and then store the new
pointer back leaving nothing to chance or compiler.

Change-Id: Ic0dedbadf85d0d0c52de69a5af72080229c03dca
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>