x86/hyperv: skip hyperv-clock test if unsupported by host

Skip the hyperv-clock tests if time reference counter is unsupported by
the host, similarly to the way other hyperv tests first check support of
the host.

Signed-off-by: Nadav Amit <nadav.amit@gmail.com>
Message-Id: <20210609182945.36849-6-nadav.amit@gmail.com>