[RHEL/6] Fix destination port typo (s/25/22/) in the iptables_sshd_disabled OVAL check

Current IPv4 case test (/etc/sysconfig/iptables) contains a typo in the dest. port number (should be 22 -- SSH, rather than 25 -- SMTP). Besides that add test_attestation & replace path+filename OVAL elements with filepath element.

Tested on RHEL-6, works fine. Please review.

Thanks, Jan.