pcspk: fix KVM

The link property that was added to the pcspk device has the wrong type:
it is only correct for TCG and for KVM's userspace or split irqchip
options.  The default KVM option (fully in-kernel irqchip) breaks
because it uses a PIT whose type is a sibling of TYPE_I8254.

Fixes: 873b4d3f
Tested-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1467298657-6588-1-git-send-email-pbonzini@redhat.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>