mac80211: Remove redundant preamble and RTS flag setup in minstrel_ht

mac80211 does the same afterwards anyway. Hence, just drop
this redundant code.
Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Acked-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/rc80211_minstrel_ht.c

@@ -519,9 +519,7 @@ minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 		rate->count = mr->retry_count;
 
 	rate->flags = IEEE80211_TX_RC_MCS | group->flags;
-	if (txrc->short_preamble)
-		rate->flags |= IEEE80211_TX_RC_USE_SHORT_PREAMBLE;
-	if (txrc->rts || rtscts)
+	if (rtscts)
 		rate->flags |= IEEE80211_TX_RC_USE_RTS_CTS;
 	rate->idx = index % MCS_GROUP_RATES + (group->streams - 1) * MCS_GROUP_RATES;
 }