net/i40e: fix missing Tx multi-segs capability

net/i40e: fix missing Tx multi-segs capability

In former API, ETH_TXQ_FLAGS_NOMULTSEGS was merely a hint indicating
that application will never send multisegmented packets, allowing
pmd to choose different tx methods accordingly.
In new API, DEV_TX_OFFLOAD_MULTI_SEGS became an offload capability
that is advertised by pmds, some of them do not advertise it and
expect to never receive fragmented packets (octeontx, axgbe)
So an ethdev that supports multisegmented packets should properly
advertise it.

Problem was spotted and tested on e1000, should be also present in
i40e_vf representor.

Fixes: e0cb96204b71 ("net/i40e: add support for representor ports")
Cc: stable@dpdk.org
Signed-off-by: Didier Pallard <didier.pallard@6wind.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>