pio_addr_t is almost unused, because these days I/O ports are simply
accessed through the address space.  cpu_{in,out}[bwl] themselves are
almost unused; monitor.c and xen-hvm.c could use address_space_read/write
directly, since they have an integer size at hand.  This leaves qtest as
the only user of those functions.

On the other hand even portio_* functions use this type; the only
interesting use of pio_addr_t thus is include/hw/sysbus.h.  I guess I
could move it there, but I don't see much benefit in that either.  Using
uint32_t is enough and avoids the need to include ioport.h everywhere.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>