drm/amdgpu: remove use_shed hack in job cleanup

Remembering the code path in a variable to cleanup
differently is usually not a good idea at all.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Monk.Liu <monk.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>