mac80211: move skb info band assignment out

Instead of passing the band as a parameter to ieee80211_xmit()
and ieee80211_tx(), move it outside of the two functions while
making sure info->band is set up before calling them.

This removes the parameter and simplifies the follow commit.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index a43a148..3ecbf68d 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -3514,6 +3514,7 @@
 
 	info->flags |= IEEE80211_TX_CTL_REQ_TX_STATUS |
 		       IEEE80211_TX_INTFL_NL80211_FRAME_TX;
+	info->band = band;
 
 	skb_set_queue_mapping(skb, IEEE80211_AC_VO);
 	skb->priority = 7;
@@ -3521,7 +3522,7 @@
 		nullfunc->qos_ctrl = cpu_to_le16(7);
 
 	local_bh_disable();
-	ieee80211_xmit(sdata, skb, band);
+	ieee80211_xmit(sdata, skb);
 	local_bh_enable();
 	rcu_read_unlock();