quota: Use register_sysctl_init() for registering fs_dqstats_table

register_sysctl_init() also prints information that may be useful for
further debugging when we fail to register sysctl table. Use it when
registering fs_dqstats_table.
Suggested-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/quota/dquot.c

@@ -2953,7 +2953,7 @@ static int __init dquot_init(void)
 
 	printk(KERN_NOTICE "VFS: Disk quotas %s\n", __DQUOT_VERSION__);
 
-	register_sysctl("fs/quota", fs_dqstats_table);
+	register_sysctl_init("fs/quota", fs_dqstats_table);
 
 	dquot_cachep = kmem_cache_create("dquot",
 			sizeof(struct dquot), sizeof(unsigned long) * 4,