amdgpu: cleanup public interface v2

Remove the mostly unused device parameter, for the few cases
where we really need it keep a copy in the context structure.

v2: rebased on internal branch

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