iwlwifi: remove rs_get_rate workaround

This removes the work around implemented for transmitting on
an unsupported band on iwlwifi. This was added via the patch:

8e1856e82cb8f541e925738bebfbc473420cda68:
iwlwifi: fix rs_get_rate WARN_ON()

Cc: Mohamed Abbas <mohamed.abbas@intel.com>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -2466,7 +2466,6 @@ static void rs_get_rate(void *priv_r, struct ieee80211_sta *sta, void *priv_sta,
 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 	struct iwl_lq_sta *lq_sta = priv_sta;
 	int rate_idx;
-	u64 mask_bit = 0;
 
 	IWL_DEBUG_RATE_LIMIT(priv, "rate scale calculate new rate for skb\n");
 
@@ -2481,18 +2480,10 @@ static void rs_get_rate(void *priv_r, struct ieee80211_sta *sta, void *priv_sta,
 			lq_sta->max_rate_idx = -1;
 	}
 
-	if (sta)
-		mask_bit = sta->supp_rates[sband->band];
-
 	/* Send management frames and NO_ACK data using lowest rate. */
 	if (!ieee80211_is_data(hdr->frame_control) ||
 	    info->flags & IEEE80211_TX_CTL_NO_ACK || !sta || !lq_sta) {
-		if (!mask_bit)
-			info->control.rates[0].idx =
-					rate_lowest_index(sband, NULL);
-		else
-			info->control.rates[0].idx =
-					rate_lowest_index(sband, sta);
+		info->control.rates[0].idx = rate_lowest_index(sband, sta);
 		if (info->flags & IEEE80211_TX_CTL_NO_ACK)
 			info->control.rates[0].count = 1;
 		return;