drm/amdgpu: suspend KFD and KGD user queues for S0ix

We need to make sure the user queues are preempted so
GFX can enter gfxoff.

Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Tested-by: David Perry <david.perry@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>