KVM: selftests: fix hyperv_clock test

The test was mistakenly using addr_gpa2hva on a gva and that happened
to work accidentally.  Commit 106a2e76 ("KVM: selftests: Lower the
min virtual address for misc page allocations") revealed this bug.

Fixes: 2c7f76b4

 ("selftests: kvm: Add basic Hyper-V clocksources tests", 2021-03-18)
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210804112057.409498-1-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>