Add cmdq completion handler for getting a notification about the
completion of cmdq commands.
Signed-off-by: NAviad Krawczyk <aviad.krawczyk@huawei.com>
Signed-off-by: NZhao Chen <zhaochen6@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>