hw/pci-host/i440fx: Make MemoryRegion pointers accessible as properties

hw/pci-host/i440fx: Make MemoryRegion pointers accessible as properties

The goal is to eliminate i440fx_init() which is a legacy init function. This
neccessitates the memory regions to be properties, like in Q35, which will be
assigned in board code.

Since i440fx needs different PCI devices in Xen mode, and since i440fx shall
be self-contained, the PCI device will be created during realization of the
host. Thus the pointers need to be moved to the host structure to be usable as
properties.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230630073720.21297-13-shentey@gmail.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>