mac80211: refactor rc_no_data_or_no_ack_use_min function

Use newly introduced helper function ieee80211_is_tx_data to check if
frame is a data frame. Takes into account that hardware encapsulation
can be enabled for a frame and therefore no ieee80211 header is present.
Signed-off-by: Philipp Borgers <borgers@mi.fu-berlin.de>
Link: https://lore.kernel.org/r/20210519122019.92359-4-borgers@mi.fu-berlin.deSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/rate.c

@@ -297,15 +297,11 @@ void ieee80211_check_rate_mask(struct ieee80211_sub_if_data *sdata)
 static bool rc_no_data_or_no_ack_use_min(struct ieee80211_tx_rate_control *txrc)
 {
 	struct sk_buff *skb = txrc->skb;
-	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
-	__le16 fc;
-
-	fc = hdr->frame_control;
 
 	return (info->flags & (IEEE80211_TX_CTL_NO_ACK |
 			       IEEE80211_TX_CTL_USE_MINRATE)) ||
-		!ieee80211_is_data(fc);
+		!ieee80211_is_tx_data(skb);
 }
 
 static void rc_send_low_basicrate(struct ieee80211_tx_rate *rate,