mxge: Sync w/ FreeBSD

- Update firmware
- Sync w/ FreeBSD if_mxge.c rev 254263

Local changes:
- Adjust output path a little bit:
  o  Utilize bus_dmamap_load_mbuf_defrag()
  o  Utilize the header length fields in mbuf pkthdr instead of
     peeking at the packet data
- Change TSO mode to NDIS mode
- Minor white space changes
- Nuke mxge_lro.c; we won't need it
build: mxge_lro.c is gone
em.4: I217 and I218 are supported by emx
tools: Add TCP_SENDFILE test to tcp_stream
in6: Fix DoS on INET6 w/ SIOCSIFADDR or SIOCSIFDSTADDR

For reference:
http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/netinet6/in6.c?rev=1.104&content-type=text/x-cvsweb-markup&only_with_tag=MAIN

DragonFly-bug: http://bugs.dragonflybsd.org/issues/2581