drm/amdgpu: remove the intterupt handling for the KIQ events

[Why]
1. we never submit IBs to the KIQ
2. there seems to be ~500ms delay during amdgpu resume spent in KIQ,
   hence pointing toward interrupts are not working correctly.

[How]
remove interrupt handling for KIQ.

Signed-off-by: Shirish S <shirish.s@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com&gt;i>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>