selinux-testsuite: move to Tier 2
    
    ...because tier 1 tests are ran for all SELinux components, which is
    alittle too often for this not-so-lightweight test.
    
    Suggested-by: Petr Lautrbach <plautrba@redhat.com>
    Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>