hw/isa/lpc_ich9: Connect PM stuff to LPC internally

hw/isa/lpc_ich9: Connect PM stuff to LPC internally

Make TYPE_ICH9_LPC_DEVICE more self-contained by moving the call to
ich9_lpc_pm_init() from board code to its realize function. In order
to propagate x86_machine_is_smm_enabled(), introduce an "smm-enabled"
property like we have in piix4.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230213173033.98762-8-shentey@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>