drm/amdgpu/pm: enable gfx_off in yellow carp smu post init

Enable gfx_off in smu_late_init for yellow carp.

Signed-off-by: Aaron Liu <aaron.liu@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>