drm/amdgpu: ungate SMC clockgating first before suspend

46c34bcb6a15dd85329a39a5e72c62108626acdc put all block’s clockgating
support in SMC. The sequence in suspend routine should be adjusted
accordingly, otherwise it causes asic hang.

Signed-off-by: Flora Cui <Flora.Cui@amd.com>
Reviewed-by: Eric Huang <JinHuiEric.Huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>