drm/amdgpu: Add IDH_QUERY_ALIVE event for SR-IOV

SR-IOV host side will send IDH_QUERY_ALIVE to guest VM to check
if this guest VM is still alive (not destroyed). The only thing
guest KMD need to do is to send ACK back to host.

Signed-off-by: Trigger Huang <Trigger.Huang@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>