program RXMAC to discard frames with SA field matching the stations's
MAC address. Experimentation shows that HME receives its own frames
when it operates at 10Mbps half-duplex. With this change HME runs at
10Mbps half-duplx should work with IPv6.
(No more "DAD detected duplicate IPv6 address".)
Reported by: jacques brierre <jbrierre AT bellsouth DOT net>
Reviewed by: marius