[PATCH] mac80211: validate VLAN interfaces better

This patch changes mac80211 to verify that VLAN interfaces
are valid and not bother drivers about them any more.
VLAN interfaces are now only valid when an AP interface
is up with the same MAC address, and are automatically
turned off when the AP interface is set down.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Cc: Jouni Malinen <j@w1.fi>
Signed-off-by: Michael Wu <flamingice@sourmilk.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>