devices: use NMPlatform to find the hardware address length

For device types that don't override it, make
nm_device_get_hw_addr_len() use NMPlatform to find out the actual
hardware address length, rather than just defaulting to ETH_ALEN.
Fixes warnings in the logs when using tun or gre devices.

src/devices/nm-device-bond.c

@@ -69,25 +69,6 @@ nm_bond_error_quark (void)
 
 /******************************************************************/
 
-static guint
-get_hw_address_length (NMDevice *device)
-{
-	GSList *slaves;
-	guint length;
-
-	/* A bond's hwaddr length depends on what kind of slaves it has;
-	 * if it has no slaves, then it doesn't have a valid hwaddr.
-	 */
-	slaves = nm_device_master_get_slaves (device);
-	if (slaves) {
-		nm_device_get_hw_address (slaves->data, &length);
-		g_slist_free (slaves);
-	} else
-		length = 0;
-
-	return length;
-}
-
 static guint32
 get_generic_capabilities (NMDevice *dev)
 {
@@ -356,7 +337,6 @@ nm_device_bond_class_init (NMDeviceBondClass *klass)
 	object_class->set_property = set_property;
 
 	parent_class->get_generic_capabilities = get_generic_capabilities;
-	parent_class->get_hw_address_length = get_hw_address_length;
 	parent_class->is_available = is_available;
 	parent_class->check_connection_compatible = check_connection_compatible;
 	parent_class->complete_connection = complete_connection;

src/devices/nm-device-bt.c

@@ -112,6 +112,17 @@ guint32 nm_device_bt_get_capabilities (NMDeviceBt *self)
 	return NM_DEVICE_BT_GET_PRIVATE (self)->capabilities;
 }
 
+static guint
+get_hw_address_length (NMDevice *device)
+{
+	NMDeviceBtPrivate *priv = NM_DEVICE_BT_GET_PRIVATE (device);
+
+	if (priv->have_iface)
+		return ETH_ALEN;
+	else
+		return 0;
+}
+
 static guint32
 get_connection_bt_type (NMConnection *connection)
 {
@@ -1260,6 +1271,7 @@ nm_device_bt_class_init (NMDeviceBtClass *klass)
 	object_class->dispose = dispose;
 	object_class->finalize = finalize;
 
+	device_class->get_hw_address_length = get_hw_address_length;
 	device_class->can_auto_connect = can_auto_connect;
 	device_class->deactivate = deactivate;
 	device_class->act_stage2_config = act_stage2_config;

src/devices/nm-device-infiniband.c

@@ -104,12 +104,6 @@ nm_device_infiniband_new (NMPlatformLink *platform_device)
 	                                  NULL);
 }
 
-static guint
-get_hw_address_length (NMDevice *device)
-{
-	return INFINIBAND_ALEN;
-}
-
 static guint32
 get_generic_capabilities (NMDevice *dev)
 {
@@ -324,7 +318,6 @@ nm_device_infiniband_class_init (NMDeviceInfinibandClass *klass)
 	object_class->set_property = set_property;
 
 	parent_class->get_generic_capabilities = get_generic_capabilities;
-	parent_class->get_hw_address_length = get_hw_address_length;
 	parent_class->check_connection_compatible = check_connection_compatible;
 	parent_class->complete_connection = complete_connection;
 

src/devices/nm-device.c

@@ -686,13 +686,21 @@ nm_device_set_ip_iface (NMDevice *self, const char *iface)
 	g_free (old_ip_iface);
 }
 
+static guint
+get_hw_address_length (NMDevice *dev)
+{
+	size_t len;
+
+	if (nm_platform_link_get_address (nm_device_get_ip_ifindex (dev), &len))
+		return len;
+	else
+		return 0;
+}
+
 static guint
 nm_device_get_hw_address_length (NMDevice *dev)
 {
-	if (NM_DEVICE_GET_CLASS (dev)->get_hw_address_length)
-		return NM_DEVICE_GET_CLASS (dev)->get_hw_address_length (dev);
-	else
-		return ETH_ALEN;
+	return NM_DEVICE_GET_CLASS (dev)->get_hw_address_length (dev);
 }
 
 const guint8 *
@@ -4972,6 +4980,7 @@ nm_device_class_init (NMDeviceClass *klass)
 	klass->hw_take_down = hw_take_down;
 	klass->carrier_changed = carrier_changed;
 	klass->can_interrupt_activation = can_interrupt_activation;
+	klass->get_hw_address_length = get_hw_address_length;
 
 	/* Properties */
 	g_object_class_install_property