drm/amdgpu: remove AMDGPU_FENCE_OWNER_MOVE

Moves are exclusive operations anyway, just use the undefined owner for those.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>