carl9170: improve site survey

The firmware keeps track of channel usage. This data can
be used by the automatic channel selection to find the
*best* channel.

Survey data from wlan22
	frequency:                      2412 MHz [in use]
	noise:                          -86 dBm
	channel active time:            3339608 ms
	channel busy time:              270982 ms
	channel transmit time:          121515 ms
Survey data from wlan22
	frequency:                      2417 MHz
	noise:                          -86 dBm
	channel active time:            70 ms
	channel busy time:              2 ms
	channel transmit time:          1 ms

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/carl9170/phy.c b/drivers/net/wireless/ath/carl9170/phy.c
index 8635c5c..472efc7 100644
--- a/drivers/net/wireless/ath/carl9170/phy.c
+++ b/drivers/net/wireless/ath/carl9170/phy.c
@@ -1573,6 +1573,9 @@
 			AR9170_PHY_EXT_CCA_MIN_PWR, phy_res[i + 2]), 8);
 	}
 
+	if (ar->channel)
+		ar->survey[ar->channel->hw_value].noise = ar->noise[0];
+
 	return 0;
 }
 
@@ -1765,10 +1768,6 @@
 		ar->chan_fail = 0;
 	}
 
-	err = carl9170_get_noisefloor(ar);
-	if (err)
-		return err;
-
 	if (ar->heavy_clip) {
 		err = carl9170_write_reg(ar, AR9170_PHY_REG_HEAVY_CLIP_ENABLE,
 					 0x200 | ar->heavy_clip);