libertas: add checks for the return value of sysfs_create_group

sysfs_create_group() could fail. The fix checkes its return values
and issue error messages if it fails.
Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/marvell/libertas/mesh.c

@@ -797,7 +797,12 @@ static void lbs_persist_config_init(struct net_device *dev)
 {
 	int ret;
 	ret = sysfs_create_group(&(dev->dev.kobj), &boot_opts_group);
+	if (ret)
+		pr_err("failed to create boot_opts_group.\n");
+
 	ret = sysfs_create_group(&(dev->dev.kobj), &mesh_ie_group);
+	if (ret)
+		pr_err("failed to create mesh_ie_group.\n");
 }
 
 static void lbs_persist_config_remove(struct net_device *dev)