hw/acpi: Move acpi_set_pci_info to pcihp

HW part of ACPI PCI hotplug in QEMU depends on ACPI_PCIHP_PROP_BSEL
being set on a PCI bus that supports ACPI hotplug. It should work
regardless of the source of ACPI tables (QEMU generator/legacy SeaBIOS/Xen).
So move ACPI_PCIHP_PROP_BSEL initialization into HW ACPI implementation
part from QEMU's ACPI table generator.

To do PCI passthrough with Xen, the property ACPI_PCIHP_PROP_BSEL needs
to be set, but this was done only when ACPI tables are built which is
not needed for a Xen guest. The need for the property starts with commit
"pc: pcihp: avoid adding ACPI_PCIHP_PROP_BSEL twice"
(f0c9d64a).

Adding find_i440fx into stubs so that mips-softmmu target can be built.

Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit ab938ae4)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>