spapr_pci: s/INT64_MAX/UINT64_MAX/

It doesn't make sense for a region to be INT64_MAX in size:
memory core uses UINT64_MAX as a special value meaning
"all 64 bit" this is what was meant here.

While this should never affect the spapr system which at the moment always
has < 63 bit size, this makes us hit all kind of corner case bugs with
sub-pages, so users are probably better off if we just use UINT64_MAX
instead.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Alexander Graf <agraf@suse.de>

hw/ppc/spapr_pci.c

@@ -555,7 +555,7 @@ static int spapr_phb_init(SysBusDevice *s)
 
     /* Initialize memory regions */
     sprintf(namebuf, "%s.mmio", sphb->dtbusname);
-    memory_region_init(&sphb->memspace, OBJECT(sphb), namebuf, INT64_MAX);
+    memory_region_init(&sphb->memspace, OBJECT(sphb), namebuf, UINT64_MAX);
 
     sprintf(namebuf, "%s.mmio-alias", sphb->dtbusname);
     memory_region_init_alias(&sphb->memwindow, OBJECT(sphb),