mt76x2: fix avg_rssi estimation

Add leftover filter coefficients in IIR rssi estimation

Fixes: 7bc04215 ("mt76: add driver code for MT76x2e")
Signed-off-by: NLorenzo Bianconi <lorenzo.bianconi@redhat.com>
Acked-by: NFelix Fietkau <nbd@nbd.name>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/mediatek/mt76/mt76x2_phy.c

@@ -508,8 +508,10 @@ mt76x2_phy_update_channel_gain(struct mt76x2_dev *dev)
 	u8 gain_delta;
 	int low_gain;
 
-	dev->cal.avg_rssi[0] = (dev->cal.avg_rssi[0] * 15) / 16 + (rssi0 << 8);
-	dev->cal.avg_rssi[1] = (dev->cal.avg_rssi[1] * 15) / 16 + (rssi1 << 8);
+	dev->cal.avg_rssi[0] = (dev->cal.avg_rssi[0] * 15) / 16 +
+			       (rssi0 << 8) / 16;
+	dev->cal.avg_rssi[1] = (dev->cal.avg_rssi[1] * 15) / 16 +
+			       (rssi1 << 8) / 16;
 	dev->cal.avg_rssi_all = (dev->cal.avg_rssi[0] +
 				 dev->cal.avg_rssi[1]) / 512;