KVM: selftests: Use TAP in the steal_time test

For easier use of the tests in automation and for having some
status information for the user while the test is running, let's
provide some TAP output in this test.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20231019095900.450467-1-thuth@redhat.com


Signed-off-by: Sean Christopherson <seanjc@google.com>