Previous commit removed the single call to isa_register_portio_list()
with dev=NULL. To be sure we won't reintroduce such weird (ab)use,
assert dev is non-NULL.

We can now calls isa_address_space_io() to get the device I/O region.

Note we can then remove the NULL check in isa_init_ioport() because
it is only called in 2 places (and is static to this file):
- isa_register_ioport() which first calls isa_address_space_io(),
  itself asserting dev is not NULL.
- isa_register_portio_list() which also asserts dev is not NULL
  since the previous commit.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/isa/isa-bus.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/hw/isa/isa-bus.c b/hw/isa/isa-bus.c
index abc1bd0771..59f98472d1 100644
--- a/hw/isa/isa-bus.c
+++ b/hw/isa/isa-bus.c
@@ -113,7 +113,7 @@ IsaDma *isa_bus_get_dma(ISABus *bus, int nchan)
 
 static inline void isa_init_ioport(ISADevice *dev, uint16_t ioport)
 {
-    if (dev && (dev->ioport_id == 0 || ioport < dev->ioport_id)) {
+    if (dev->ioport_id == 0 || ioport < dev->ioport_id) {
         dev->ioport_id = ioport;
     }
 }
@@ -129,6 +129,7 @@ int isa_register_portio_list(ISADevice *dev,
                              const MemoryRegionPortio *pio_start,
                              void *opaque, const char *name)
 {
+    assert(dev);
     assert(piolist && !piolist->owner);
 
     if (!isabus) {
@@ -141,7 +142,7 @@ int isa_register_portio_list(ISADevice *dev,
     isa_init_ioport(dev, start);
 
     portio_list_init(piolist, OBJECT(dev), pio_start, opaque, name);
-    portio_list_add(piolist, isabus->address_space_io, start);
+    portio_list_add(piolist, isa_address_space_io(dev), start);
 
     return 0;
 }
-- 
2.38.1