drm/amdgpu: Add tlb_cb for unlocked update

Flush TLB needs wait for GPU update fence done. MMU notify callback to
unmap range from GPUs uses unlocked GPU page table update, so add tlb_cb
to unlocked update fence to increase vm->tlb_seq.

Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>