KVM: selftests: x86: Add vmx_nested_tsc_scaling_test

Test that nested TSC scaling works as expected with both L1 and L2
scaled.

Signed-off-by: Ilias Stamatis <ilstam@amazon.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210526184418.28881-12-ilstam@amazon.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>