hw/i386/pc: Have pc_init_isa() pass a NULL pci_type argument

The "isapc" machine only provides an ISA bus, not a PCI one,
and doesn't instanciate any i440FX south bridge.
Its machine class defines PCMachineClass::pci_enabled = false,
and pc_init1() only uses the pci_type argument when pci_enabled
is true. Since for this machine the argument is not used,
passing NULL makes more sense.

Signed-off-by: Philippe Mathieu-Daudé <[email protected]>
Reviewed-by: Bernhard Beschow <[email protected]>
Message-Id: <[email protected]>

hw/i386/pc_piix.c

@@ -450,7 +450,7 @@ static void pc_compat_2_0_fn(MachineState *machine)
 #ifdef CONFIG_ISAPC
 static void pc_init_isa(MachineState *machine)
 {
-    pc_init1(machine, TYPE_I440FX_PCI_DEVICE);
+    pc_init1(machine, NULL);
 }
 #endif