msm: kgsl: Correct the logic for isdb breakpoint set

Isdb registers have to be written when the hardware clock gating is off.
Correct the logic to reflect that.

Change-Id: Ic16d316b40649481e0d3b8dc5dfb980c87960a17
Signed-off-by: Mohammed Mirza Mandayappurath Manzoor <mmandaya@codeaurora.org>