hw/acpi/aml-build: Build a root node in the PPTT table

hw/acpi/aml-build: Build a root node in the PPTT table

Currently we build the PPTT starting from the socket node and each
socket will be a separate tree. For a multi-socket system it'll
be hard for the OS to know the whole system is homogeneous or not
(actually we're in the current implementation) since no parent node
to telling the identical implementation informentation. Add a
root node for indicating this.

Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Alireza Sanaee <alireza.sanaee@huawei.com>
Message-Id: <20250714173146.511-4-alireza.sanaee@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>