wcn36xx: fix RX BD rate mapping for 5GHz legacy rates

The linear mapping between the BD rate field and the driver's 5GHz
legacy rates table (wcn_5ghz_rates) does not only apply for the latter
four rates -- it applies to all eight rates.

Fixes: 6ea131ac ("wcn36xx: Fix warning due to bad rate_idx")
Signed-off-by: Benjamin Li <benl@squareup.com>
Tested-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211104010548.1107405-3-benl@squareup.com

drivers/net/wireless/ath/wcn36xx/txrx.c

@@ -272,7 +272,6 @@ int wcn36xx_rx_skb(struct wcn36xx *wcn, struct sk_buff *skb)
 	const struct wcn36xx_rate *rate;
 	struct ieee80211_hdr *hdr;
 	struct wcn36xx_rx_bd *bd;
-	struct ieee80211_supported_band *sband;
 	u16 fc, sn;
 
 	/*
@@ -350,12 +349,11 @@ int wcn36xx_rx_skb(struct wcn36xx *wcn, struct sk_buff *skb)
 		status.enc_flags = rate->encoding_flags;
 		status.bw = rate->bw;
 		status.rate_idx = rate->mcs_or_legacy_index;
-		sband = wcn->hw->wiphy->bands[status.band];
 		status.nss = 1;
 
 		if (status.band == NL80211_BAND_5GHZ &&
 		    status.encoding == RX_ENC_LEGACY &&
-		    status.rate_idx >= sband->n_bitrates) {
+		    status.rate_idx >= 4) {
 			/* no dsss rates in 5Ghz rates table */
 			status.rate_idx -= 4;
 		}