ethdev: fix item expansion for RSS flow

ethdev: fix item expansion for RSS flow

When the last item in flow pattern includes "next protocol" field which
is relevant for RSS flow expansion, a new item is added to the pattern
according to the "next protocol" field. This field is called missed
field.

The missed field wrongly was not initialized what caused to some of the
flow item fields to contain garbage values.

As a result, the PMDs internal flow engine may crash.

For example, the spec value may include garbage pointer and to cause
crash.

Initialize the missed field with zeroes.

Fixes: fc2dd8dd492f ("ethdev: fix expand RSS flows")
Cc: stable@dpdk.org
Signed-off-by: Matan Azrad <matan@mellanox.com>
Acked-by: Ori Kam <orika@mellanox.com>