drm/amdgpu: use scheduler load balancing for compute CS

Start to use the scheduler load balancing for userspace compute
command submissions.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>