softmmu/ioport.c: QOMify MemoryRegionPortioList

softmmu/ioport.c: QOMify MemoryRegionPortioList

The aim of QOMification is so that the lifetime of the MemoryRegionPortioList
structure can be managed using QOM's in-built refcounting instead of having to
handle this manually.

Due to the use of an opaque pointer it isn't possible to model the new
TYPE_MEMORY_REGION_PORTIO_LIST directly using QOM properties, however since
use of the new object is restricted to the portio API we can simply set the
opaque pointer (and the heap-allocated port list) internally.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230419151652.362717-3-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>