ath9k: Do not set IEEE80211_TX_RC_USE_SHORT_PREAMBLE

mac80211 does it for us.
Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/rc.c

@@ -682,8 +682,6 @@ static void ath_rc_rate_set_series(const struct ath_rate_table *rate_table,
 	rate->count = tries;
 	rate->idx = rate_table->info[rix].ratecode;
 
-	if (txrc->short_preamble)
-		rate->flags |= IEEE80211_TX_RC_USE_SHORT_PREAMBLE;
 	if (txrc->rts || rtsctsenable)
 		rate->flags |= IEEE80211_TX_RC_USE_RTS_CTS;