mac80211: fix wiphy supported_band access

Fix wiphy supported_band access in tx radiotap parsing introduced
in commit 5ec3aed9ba4c ("mac80211: Parse legacy and HT rate in
injected frames"). In particular, info->band is always set to 0
(IEEE80211_BAND_2GHZ) since it has not assigned yet.
This cause a kernel crash on 5GHz only devices.
Move ieee80211_parse_tx_radiotap() after info->band assignment

Signed-off-by: Lorenzo Bianconi <[e-mail]>
Signed-off-by: Johannes Berg <[e-mail]>

net/mac80211/tx.c

···
 	info->flags = IEEE80211_TX_CTL_REQ_TX_STATUS |
 		      IEEE80211_TX_CTL_INJECTED;
 
-	/* process and remove the injection radiotap header */
-	if (!ieee80211_parse_tx_radiotap(local, skb))
-		goto fail;
-
 	rcu_read_lock();
 
 	/*
···
 		goto fail_rcu;
 
 	info->band = chandef->chan->band;
+
+	/* process and remove the injection radiotap header */
+	if (!ieee80211_parse_tx_radiotap(local, skb))
+		goto fail_rcu;
+
 	ieee80211_xmit(sdata, NULL, skb);
 	rcu_read_unlock();