mac80211: split IBSS/managed code

This patch splits out the ibss code and data from managed (station) mode.
The reason to do this is to better separate the state machines, and have
the code be contained better so it gets easier to determine what exactly
a given change will affect, that in turn makes it easier to understand.

This is quite some churn, especially because I split sdata->u.sta into
sdata->u.mgd and sdata->u.ibss, but I think it's easier to maintain that
way. I've also shuffled around some code -- null function sending is only
applicable to managed interfaces so put that into that file, some other
functions are needed from various places so put them into util, and also
rearranged the prototypes in ieee80211_i.h accordingly.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 6aca498..c3f0e95 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1633,7 +1633,7 @@
 	case NL80211_IFTYPE_STATION:
 		fc |= cpu_to_le16(IEEE80211_FCTL_TODS);
 		/* BSSID SA DA */
-		memcpy(hdr.addr1, sdata->u.sta.bssid, ETH_ALEN);
+		memcpy(hdr.addr1, sdata->u.mgd.bssid, ETH_ALEN);
 		memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
 		memcpy(hdr.addr3, skb->data, ETH_ALEN);
 		hdrlen = 24;
@@ -1642,7 +1642,7 @@
 		/* DA SA BSSID */
 		memcpy(hdr.addr1, skb->data, ETH_ALEN);
 		memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
-		memcpy(hdr.addr3, sdata->u.sta.bssid, ETH_ALEN);
+		memcpy(hdr.addr3, sdata->u.ibss.bssid, ETH_ALEN);
 		hdrlen = 24;
 		break;
 	default:
@@ -1928,7 +1928,6 @@
 	struct ieee80211_tx_info *info;
 	struct ieee80211_sub_if_data *sdata = NULL;
 	struct ieee80211_if_ap *ap = NULL;
-	struct ieee80211_if_sta *ifsta = NULL;
 	struct beacon_data *beacon;
 	struct ieee80211_supported_band *sband;
 	enum ieee80211_band band = local->hw.conf.channel->band;
@@ -1980,13 +1979,13 @@
 		} else
 			goto out;
 	} else if (sdata->vif.type == NL80211_IFTYPE_ADHOC) {
+		struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
 		struct ieee80211_hdr *hdr;
-		ifsta = &sdata->u.sta;
 
-		if (!ifsta->probe_resp)
+		if (!ifibss->probe_resp)
 			goto out;
 
-		skb = skb_copy(ifsta->probe_resp, GFP_ATOMIC);
+		skb = skb_copy(ifibss->probe_resp, GFP_ATOMIC);
 		if (!skb)
 			goto out;