mt76: Use the correct hweight8() function

mt76_init_stream_cap() and mt76_get_txpower() call __sw_hweight8()
directly, but that's only defined if CONFIG_GENERIC_HWEIGHT is
enabled.  The function that works on all architectures is hweight8().

Fixes: 551e1ef4 ("mt76: add mt76_init_stream_cap routine")
Fixes: 9313faac ("mt76: move mt76x02_get_txpower to mt76 core")
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mac80211.c

@@ -124,7 +124,7 @@ static void mt76_init_stream_cap(struct mt76_dev *dev,
 				 bool vht)
 {
 	struct ieee80211_sta_ht_cap *ht_cap = &sband->ht_cap;
-	int i, nstream = __sw_hweight8(dev->antenna_mask);
+	int i, nstream = hweight8(dev->antenna_mask);
 	struct ieee80211_sta_vht_cap *vht_cap;
 	u16 mcs_map = 0;
 
@@ -726,7 +726,7 @@ int mt76_get_txpower(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 		     int *dbm)
 {
 	struct mt76_dev *dev = hw->priv;
-	int n_chains = __sw_hweight8(dev->antenna_mask);
+	int n_chains = hweight8(dev->antenna_mask);
 
 	*dbm = dev->txpower_cur / 2;