msm: kgsl: Wait additional 50ms for CP to complete preemption

We observed CP preemption state to be busy even after preemption
interrupt is triggered by CP. If CP preemption state is busy after
preemption interrupt is triggered, instead of triggering a GPU hang
immediately give CP additional 50ms to update the state to be
preemption complete. If CP state is not updated after 50ms, trigger a
GPU hang.

Change-Id: I27a3bbd8efa9aa932dc9b185457099ca4358e83a
Signed-off-by: Tarun Karra <tkarra@codeaurora.org>