msm: kgsl: Add L3 performance hint

Add software path to bump the l3 frequency using a
performance hint from user space in I/O coherence cases.

Change-Id: I559fecf0dbbf79ebe3972db2a65bde6b69063fc9
Signed-off-by: Urvashi Agrawal <urvaagra@codeaurora.org>
Signed-off-by: Lynus Vaz <lvaz@codeaurora.org>