KVM: selftests: Rename 'msr->available' to 'msr->fault_exepected' in hyperv_features test

It may not be clear what 'msr->available' means. The test actually
checks that accessing the particular MSR doesn't cause #GP, rename
the variable accordingly.

While on it, use 'true'/'false' instead of '1'/'0' for 'write'/
'fault_expected' as these are boolean.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221013095849.705943-5-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>