rt2x00: Improve interface_modes initialization

All operating modes which require beaconing should
depend on the availability of beacon entries from
the hardware.
Signed-off-by: NIvo van Doorn <IvDoorn@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/rt2x00dev.c

@@ -1056,10 +1056,16 @@ int rt2x00lib_probe_dev(struct rt2x00_dev *rt2x00dev)
 	 */
 	rt2x00dev->hw->vif_data_size = sizeof(struct rt2x00_intf);
 
-	rt2x00dev->hw->wiphy->interface_modes =
-	    BIT(NL80211_IFTYPE_AP) |
-	    BIT(NL80211_IFTYPE_STATION) |
-	    BIT(NL80211_IFTYPE_ADHOC);
+	/*
+	 * Determine which operating modes are supported, all modes
+	 * which require beaconing, depend on the availability of
+	 * beacon entries.
+	 */
+	rt2x00dev->hw->wiphy->interface_modes = BIT(NL80211_IFTYPE_STATION);
+	if (rt2x00dev->ops->bcn->entry_num > 0)
+		rt2x00dev->hw->wiphy->interface_modes |=
+		    BIT(NL80211_IFTYPE_ADHOC) |
+		    BIT(NL80211_IFTYPE_AP);
 
 	/*
 	 * Let the driver probe the device to detect the capabilities.