[dts] [PATCH V1] tests/vhost_user_live_migration: delete dequeue-zero-copy parameter

[Tu, Lijuan]

> As DPDK community will remove support dequeue zero copy feature in 20.11,so
> remove dequeue-zero-copy parameter when start testpmd.
> 
> Signed-off-by: Ling Wei <weix.ling at intel.com>

Test plan need to update at the same time, thanks