KVM: selftests: Make hyperv_clock require TSC based system clocksource

KVM: selftests: Make hyperv_clock require TSC based system clocksource

KVM sets up Hyper-V TSC page clocksource for its guests when system
clocksource is 'based on TSC' (see gtod_is_based_on_tsc()), running
hyperv_clock with any other clocksource leads to imminent failure.

Add the missing requirement to make the test skip gracefully.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20240109141121.1619463-5-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>