There is no guarantee that the last BO_VA actually needed an update.

Additional to that all command submissions must wait for moved BOs to
be cleared, not just the first one.

v2: Don't overwrite any newer fence.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>