drm/amdgpu/ci: drop some old thermal setup

This was leftover from a long time ago and is not longer needed
since the thermal controller setup code was added.  Additional
mucking with the thermal interrupts can cause spurious thermal
events which can lead to unnecessary state changes.

Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Ken Wang <Qingqing.Wang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>