In STA mode, the AP will echo our traffic.  This includes multicast
traffic.

Receiving these frames confuses some protocols and applications,
notably IPv6 Duplicate Address Detection.
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Acked-by: NMichael Wu <flamingice@sourmilk.net>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>