hw/i386/acpi-build: Determine SMI command port just once

hw/i386/acpi-build: Determine SMI command port just once

The SMI command port is currently hardcoded by means of the ACPI_PORT_SMI_CMD
macro. This hardcoding is Intel specific and doesn't match VIA, for example.
There is already the AcpiFadtData::smi_cmd attribute which is used when building
the FADT. Let's also use it when building the DSDT which confines SMI command
port determination to just one place. This allows it to become a property later,
thus resolving the Intel assumption.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230908084234.17642-7-shentey@gmail.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>