loopback: off by one in tcm_loop_make_naa_tpg()

This is an off by one 'tgpt' check in tcm_loop_make_naa_tpg() that could result
in memory corruption.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
static void tcm_loop_deregister_configfs(void)
{
	if (!tcm_loop_fabric_configfs)
		return;

	target_fabric_configfs_deregister(tcm_loop_fabric_configfs);
	tcm_loop_fabric_configfs = NULL;
	printk(KERN_INFO "TCM_LOOP[0] - Cleared"
				" tcm_loop_fabric_configfs\n");
}

static void tcm_loop_deregister_configfs(void)
{
	if (!tcm_loop_fabric_configfs)
		return;

	target_fabric_configfs_deregister(tcm_loop_fabric_configfs);
	tcm_loop_fabric_configfs = NULL;
	printk(KERN_INFO "TCM_LOOP[0] - Cleared"
				" tcm_loop_fabric_configfs\n");
}
