[dts] [PATCH v2] test_plans/flexible_rxd_test_plan:add MPLS cases

[Tu, Lijuan]

> > v1: add MPLS test cases.
> > v2: modify hierarc.
> >
> > Signed-off-by: Hailin Xu <hailinx.xu at intel.com>
> Acked-by: Lin Xueqin <Xueqin.lin at intel.com>

Applied.