app/testpmd: fix MPLSoUDP encapsulation

app/testpmd: fix MPLSoUDP encapsulation

In function cmd_set_mplsoudp_encap_parsed(), MPLS label value was
set in mplsoudp_encap_conf struct without the required offset.
As a result the value was copied incorrectly into
rte_flow_item_mpls struct.

This patch sets MPLS label value in appropriate location at
mplsoudp_encap_conf struct, so it is correctly copied to
rte_flow_item_mpls struct.

Fixes: a1191d39cb57 ("app/testpmd: add MPLSoUDP encapsulation")
Cc: stable@dpdk.org
Signed-off-by: Dekel Peled <dekelp@mellanox.com>
Acked-by: Ori Kam <orika@mellanox.com>