ext4: null out kobject* during sysfs cleanup

Make cleanup of ext4_feat kobject consistent with similar objects.

Signed-off-by: Tyson Nottingham <tgnottingham@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/sysfs.c

@@ -464,6 +464,7 @@ int __init ext4_init_sysfs(void)
 
 feat_err:
 	kobject_put(ext4_feat);
+	ext4_feat = NULL;
 kset_err:
 	kset_unregister(ext4_kset);
 	ext4_kset = NULL;
@@ -473,6 +474,7 @@ kset_err:
 void ext4_exit_sysfs(void)
 {
 	kobject_put(ext4_feat);
+	ext4_feat = NULL;
 	kset_unregister(ext4_kset);
 	ext4_kset = NULL;
 	remove_proc_entry(proc_dirname, NULL);