ioport: use INT64_MAX for IO ranges

Expression UINT64_MAX + 1 will make the range bigger than
what can be represented with a 64 bit type. This would
trigger an assert in int128_get64() after the next patch.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

ioport.c

diff --git a/ioport.c b/ioport.c
index 78a3b89..6e4ca0d 100644
--- a/ioport.c
+++ b/ioport.c
@@ -385,7 +385,7 @@
      * rather than an offset relative to to start + off_low.
      */
     memory_region_init_io(region, ops, piolist->opaque, piolist->name,
-                          UINT64_MAX);
+                          INT64_MAX);
     memory_region_init_alias(alias, piolist->name,
                              region, start + off_low, off_high - off_low);
     memory_region_add_subregion(piolist->address_space,