ap: Fix return value in hostapd_drv_switch_channel()

The documentation in driver.h state that in case of an error
-1 is returned.

Signed-off-by: Ilan Peer <ilan.peer@intel.com>

src/ap/ap_drv_ops.h

@@ -276,7 +276,7 @@ static inline int hostapd_drv_switch_channel(struct hostapd_data *hapd,
 {
 	if (hapd->driver == NULL || hapd->driver->switch_channel == NULL ||
 	    hapd->drv_priv == NULL)
-		return -ENOTSUP;
+		return -1;
 
 	return hapd->driver->switch_channel(hapd->drv_priv, settings);
 }