Revert "drm/scheduler: improve job distribution with multiple queues"

It needs to revert this patch to avoid amdgpu_test compute hang problem
on picasso.

This reverts commit 56822db1.

Signed-off-by: changzhu <Changfeng.Zhu@amd.com>
Reviewed-by: Feifei Xu <Feifei.Xu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>