KVM: selftests: x86: Use TAP interface in the tsc_msrs_test

Let's add some output here so that the user has some feedback
about what is being run.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20221004093131.40392-4-thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>