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 char *tcm_loop_get_endpoint_wwn(struct se_portal_group *se_tpg)
{
	struct tcm_loop_tpg *tl_tpg =
		(struct tcm_loop_tpg *)se_tpg->se_tpg_fabric_ptr;
	/*
	 * Return the passed NAA identifier for the SAS Target Port
	 */
	return &tl_tpg->tl_hba->tl_wwn_address[0];
}

static char *tcm_loop_get_endpoint_wwn(struct se_portal_group *se_tpg)
{
	struct tcm_loop_tpg *tl_tpg =
		(struct tcm_loop_tpg *)se_tpg->se_tpg_fabric_ptr;
	/*
	 * Return the passed NAA identifier for the SAS Target Port
	 */
	return &tl_tpg->tl_hba->tl_wwn_address[0];
}
