wireless: report reasonable bitrate for MCS rates through wext

Previously, cfg80211 had reported "0" for MCS (i.e. 802.11n) bitrates
through the wireless extensions interface.  However, nl80211 was
converting MCS rates into a reasonable bitrate number.  This patch moves
the nl80211 code to cfg80211 where it is now shared between both the
nl80211 interface and the wireless extensions interface.

Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index a602843..7cb0d64 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -1637,39 +1637,6 @@
 	return 0;
 }
 
-static u16 nl80211_calculate_bitrate(struct rate_info *rate)
-{
-	int modulation, streams, bitrate;
-
-	if (!(rate->flags & RATE_INFO_FLAGS_MCS))
-		return rate->legacy;
-
-	/* the formula below does only work for MCS values smaller than 32 */
-	if (rate->mcs >= 32)
-		return 0;
-
-	modulation = rate->mcs & 7;
-	streams = (rate->mcs >> 3) + 1;
-
-	bitrate = (rate->flags & RATE_INFO_FLAGS_40_MHZ_WIDTH) ?
-			13500000 : 6500000;
-
-	if (modulation < 4)
-		bitrate *= (modulation + 1);
-	else if (modulation == 4)
-		bitrate *= (modulation + 2);
-	else
-		bitrate *= (modulation + 3);
-
-	bitrate *= streams;
-
-	if (rate->flags & RATE_INFO_FLAGS_SHORT_GI)
-		bitrate = (bitrate / 9) * 10;
-
-	/* do NOT round down here */
-	return (bitrate + 50000) / 100000;
-}
-
 static int nl80211_send_station(struct sk_buff *msg, u32 pid, u32 seq,
 				int flags, struct net_device *dev,
 				u8 *mac_addr, struct station_info *sinfo)
@@ -1716,8 +1683,8 @@
 		if (!txrate)
 			goto nla_put_failure;
 
-		/* nl80211_calculate_bitrate will return 0 for mcs >= 32 */
-		bitrate = nl80211_calculate_bitrate(&sinfo->txrate);
+		/* cfg80211_calculate_bitrate will return 0 for mcs >= 32 */
+		bitrate = cfg80211_calculate_bitrate(&sinfo->txrate);
 		if (bitrate > 0)
 			NLA_PUT_U16(msg, NL80211_RATE_INFO_BITRATE, bitrate);