selftests/powerpc: Skip security tests on older CPUs

Both these tests use PMU events that only work on newer CPUs, so skip
them on older CPUs.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200819015727.1977134-6-mpe@ellerman.id.au
2 files changed