drm/amdgpu: add the new common pm code to support sclk OD

This extends OD (OverDrive) support to the non-Powerplay code paths.

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