wlcore: add antenna diversity reading comments

add comments to the antenna diversity reading
Signed-off-by: Guy Mishol <guym@ti.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ti/wlcore/rx.c

@@ -74,6 +74,12 @@ static void wl1271_rx_status(struct wl1271 *wl,
 	if (desc->rate <= wl->hw_min_ht_rate)
 		status->flag |= RX_FLAG_HT;
 
+	/*
+	* Read the signal level and antenna diversity indication.
+	* The msb in the signal level is always set as it is a
+	* negative number.
+	* The antenna indication is the msb of the rssi.
+	*/
 	status->signal = ((desc->rssi & RSSI_LEVEL_BITMASK) | BIT(7));
 	status->antenna = ((desc->rssi & ANT_DIVERSITY_BITMASK) >> 7);