app/testpmd: fix packet segment allocation

app/testpmd: fix packet segment allocation

When --mbuf-size cmdline parameter is specified, the segments to scatter
packets on are allocated sequentially from these extra memory pools
(the mbuf for the first segment is allocated from the first pool, the
second one from the second pool, and so on, if segment number is greater
then pool’s the mbuf for remaining segments will be allocated from the
last valid pool).
A bug in comparing segment index with mbuf index caused wrong mapping
of one of the segments.

Fix the comparison.

Fixes: 2befc67ff679 ("app/testpmd: add extended Rx queue setup")
Cc: stable@dpdk.org
Signed-off-by: Raja Zidane <rzidane@nvidia.com>
Acked-by: Matan Azrad <matan@nvidia.com>