[gnome-control-center] network: Avoid crashing if the NMDevice doesn't have a hw-address

[Rui Matos <rtcm src gnome org>]

commit ca667d9928783423d8ff8f3e8a5dc9ac1626334e
Author: Rui Matos <tiagomatos gmail com>
Date:   Fri Jun 16 12:24:05 2017 +0200

    network: Avoid crashing if the NMDevice doesn't have a hw-address
    
    The property might not exist and we would g_free() an uninitialized
    pointer. Using the proper API avoids all that.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=783839

 panels/network/net-device-simple.c |    7 ++-----
 1 files changed, 2 insertions(+), 5 deletions(-)
---
diff --git a/panels/network/net-device-simple.c b/panels/network/net-device-simple.c
index 3a3c2c9..79b6ca3 100644
--- a/panels/network/net-device-simple.c
+++ b/panels/network/net-device-simple.c
@@ -85,7 +85,7 @@ static void
 nm_device_simple_refresh_ui (NetDeviceSimple *device_simple)
 {
         NetDeviceSimplePrivate *priv = device_simple->priv;
-        char *hwaddr;
+        const char *hwaddr;
         GtkWidget *widget;
         char *speed = NULL;
         NMDevice *nm_device;
@@ -119,11 +119,8 @@ nm_device_simple_refresh_ui (NetDeviceSimple *device_simple)
         panel_set_device_status (priv->builder, "label_status", nm_device, speed);
 
         /* device MAC */
-        g_object_get (G_OBJECT (nm_device),
-                      "hw-address", &hwaddr,
-                      NULL);
+        hwaddr = nm_device_get_hw_address (nm_device);
         panel_set_device_widget_details (priv->builder, "mac", hwaddr);
-        g_free (hwaddr);
 
         /* set IP entries */
         panel_set_device_widgets (priv->builder, nm_device);