msm: kgsl: Refactor the A6XX protection ranges

Simplify the code that initializes the A6XX protection ranges
and fix a compile error.

Change-Id: I2f574ff21a5629e94c062b7cbf5ec338f28d7691
Signed-off-by: Lynus Vaz <lvaz@codeaurora.org>
Signed-off-by: Tarun Karra <tkarra@codeaurora.org>