mac80211: revamp beacon configuration

This patch changes mac80211's beacon configuration handling
to never pass skbs to the driver directly but rather always
require the driver to use ieee80211_beacon_get(). Additionally,
it introduces "change flags" on the config_interface() call
to enable drivers to figure out what is changing. Finally, it
removes the beacon_update() driver callback in favour of
having IBSS beacon delivered by ieee80211_beacon_get() as well.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2500pci.c b/drivers/net/wireless/rt2x00/rt2500pci.c
index 0423c25..a64bb18 100644
--- a/drivers/net/wireless/rt2x00/rt2500pci.c
+++ b/drivers/net/wireless/rt2x00/rt2500pci.c
@@ -1875,7 +1875,6 @@
 	.conf_tx		= rt2x00mac_conf_tx,
 	.get_tx_stats		= rt2x00mac_get_tx_stats,
 	.get_tsf		= rt2500pci_get_tsf,
-	.beacon_update		= rt2500pci_beacon_update,
 	.tx_last_beacon		= rt2500pci_tx_last_beacon,
 };
 
@@ -1895,6 +1894,7 @@
 	.write_tx_data		= rt2x00pci_write_tx_data,
 	.kick_tx_queue		= rt2500pci_kick_tx_queue,
 	.fill_rxdone		= rt2500pci_fill_rxdone,
+	.beacon_update		= rt2500pci_beacon_update,
 	.config_filter		= rt2500pci_config_filter,
 	.config_intf		= rt2500pci_config_intf,
 	.config_erp		= rt2500pci_config_erp,