msm: kgsl: Extend GMU idle timeout.

Profiling results show that there are corner cases when
default 10ms timeout for GMU idle is not enough. As per
conversation with HW team we'll use 100ms timeout

CRs-Fixed: 2126674
Signed-off-by: Oleg Perelet <operelet@codeaurora.org>
Change-Id: I47f8fa55a4139397b96a90046df36fee2e4553d9