KVM: selftests: Avoid infinite loop in hyperv_features when invtsc is missing

KVM: selftests: Avoid infinite loop in hyperv_features when invtsc is missing

When X86_FEATURE_INVTSC is missing, guest_test_msrs_access() was supposed
to skip testing dependent Hyper-V invariant TSC feature. Unfortunately,
'continue' does not lead to that as stage is not incremented. Moreover,
'vm' allocated with vm_create_with_one_vcpu() is not freed and the test
runs out of available file descriptors very quickly.

Fixes: bd827bd77537 ("KVM: selftests: Test Hyper-V invariant TSC control")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20240129085847.2674082-1-vkuznets@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>