o Fix the packet statistics
o Make sure we set the FD bit when in full duplex
o Improve TX side efficency by eliminating a data copy for
unfragmented mbufs (the hardware can't do s/g).
o Minor busdma pedantry
o better comments in some places, more XXX in others
o Minor style nits.
This solves a problem I was seeing where I'd get no ethernet when not
booting with a NFS root. Well, unless I unplugged the cable and
plugged it back in first so I'd get the same up down up messages I get
for NFS root...
Thanks to sam and scottl for suggestions on making this driver more
efficient through better use of approrpiate APIs.