KVM: selftests: Fix MWAIT error message when guest assertion fails

KVM: selftests: Fix MWAIT error message when guest assertion fails

Print out the test and vector as intended when a guest assert fails an
assertion regarding MONITOR/MWAIT faulting.  Unfortunately, the guest
printf support doesn't detect such issues at compile-time, so the bug
manifests as a confusing error message, e.g. in the most confusing case,
the test complains that it got vector "0" instead of expected vector "0".

Fixes: 0f52e4aaa614 ("KVM: selftests: Convert the MONITOR/MWAIT test to use printf guest asserts")
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20231107182159.404770-1-seanjc@google.com
Link: https://lore.kernel.org/r/20231129224916.532431-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>