Revert "drm/amdkfd: Improve signal event slow path"

Revert "drm/amdkfd: Improve signal event slow path"

To fix regression report on gfx8, which requires the exhaustive search
path for signaled event.

The high CPU usage of KFD interrupt wq issue is gone after HIP/ROCr add
option to reduce HW event interrupts, safe to revert this optimization
patch now.

This reverts commit de844846f72b152119faaef1b363448dc8ea368f.

Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>