Staging: batman-adv: Ignore debugfs on kernels without debugfs support

All code for debugfs is ignored when the creation of the batman-adv root
directory in debugfs fails. It must also be ignored when the
debugfs_create_dir tells us that debugfs is not implemented to prevent
possible crashes in the future.
Signed-off-by: Sven Eckelmann <sven.eckelmann@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/batman-adv/bat_debugfs.c

@@ -88,6 +88,8 @@ static struct bat_debuginfo *mesh_debuginfos[] = {
 void debugfs_init(void)
 {
 	bat_debugfs = debugfs_create_dir(DEBUGFS_BAT_SUBDIR, NULL);
+	if (bat_debugfs == ERR_PTR(-ENODEV))
+		bat_debugfs = NULL;
 }
 
 void debugfs_destroy(void)