mac80211: allow driver to prevent two stations w/ same address

mac80211: allow driver to prevent two stations w/ same address

commit 3110489117581a980537b6d999a3724214ba772c upstream.

Some devices or drivers cannot deal with having the same station
address for different virtual interfaces, say as a client to two
virtual AP interfaces. Rather than requiring each driver with a
limitation like that to enforce it, add a hardware flag for it.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>