The new amdgpu_gfx_state_change_set() funtion can support set GFX power
change status to D0/D3.

v2: squash in warning fix (Alex)
Signed-off-by: NPrike Liang <Prike.Liang@amd.com>
Acked-by: NHuang Rui <ray.huang@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>