drm/amdgpu: add backend implementation of gpu scheduler (v2)

v2: fix rebase breakage

Signed-off-by: Chunming Zhou <david1.zhou@amd.com>
Acked-by: Christian K?nig <christian.koenig@amd.com>
Reviewed-by: Jammy Zhou <Jammy.Zhou@amd.com>
4 files changed