tools: Fix virt-host-validate SEV detection

tools: Fix virt-host-validate SEV detection

virt-host-validate checks if AMD SEV is enabled by verifying
/sys/module/kvm_amd/parameters/sev is set to '1'. On a system
running kernel 5.13, the parameter is reported as 'Y'. To be
extra paranoid, add a check for 'y' along with 'Y' to complement
the existing check for '1'.

Fixes: https://bugzilla.opensuse.org/show_bug.cgi?id=1188715
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Reviewed-by: Andrea Bolognani <abologna@redhat.com>