Version 2 of the patch. Added checks for version 0
and proper from/to DS bits. Even in promisc
mode we won't receive packets from another BSSes.

bcm43xx_rx() contains code to filter out packets from
foreign BSSes and decide whether to call ieee80211_rx
or ieee80211_rx_mgt. This is not bcm specific.

Patch adapts that code and adds it to 80211
as ieee80211_rx_any() function.
Signed-off-by: NDenis Vlasenko <vda@ilport.com.ua>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>