sfxge(4): support MARK and FLAG actions in filters

This patch adds support for DPDK rte_flow "MARK" and "FLAG" filter
actions to filters on EF10 family NICs.

Submitted by: Roman Zhukov <roman.zhukov at oktetlabs.ru>
Sponsored by: Solarflare Communications, Inc.
Differential Revision: https://reviews.freebsd.org/D18239