iwlagn: iwl-agn-rs: remove unnecessary null check for sta and lq_sta

both sta and lq_sta are guaranteed to be not null in the
calling function so we don't need to check them here.
Signed-off-by: Greg Dietsche <Gregory.Dietsche@cuw.edu>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-agn-rs.c

@@ -2273,9 +2273,6 @@ static void rs_rate_scale_perform(struct iwl_priv *priv,
 	    info->flags & IEEE80211_TX_CTL_NO_ACK)
 		return;
 
-	if (!sta || !lq_sta)
-		return;
-
 	lq_sta->supp_rates = sta->supp_rates[lq_sta->band];
 
 	tid = rs_tl_add_packet(lq_sta, hdr);