wl1271: add get_survey callback in order to get channel noise

Signed-off-by: John W. Linville <linville@tuxdriver.com>
Acked-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
diff --git a/drivers/net/wireless/wl12xx/wl1271_rx.c b/drivers/net/wireless/wl12xx/wl1271_rx.c
index e98f22b..019aa79 100644
--- a/drivers/net/wireless/wl12xx/wl1271_rx.c
+++ b/drivers/net/wireless/wl12xx/wl1271_rx.c
@@ -55,6 +55,13 @@
 
 	status->signal = desc->rssi;
 
+	/*
+	 * FIXME: In wl1251, the SNR should be divided by two.  In wl1271 we
+	 * need to divide by two for now, but TI has been discussing about
+	 * changing it.  This needs to be rechecked.
+	 */
+	wl->noise = desc->rssi - (desc->snr >> 1);
+
 	status->freq = ieee80211_channel_to_frequency(desc->channel);
 
 	if (desc->flags & WL1271_RX_DESC_ENCRYPT_MASK) {