isa: add isa_register_ioport() To replace isa_init_ioport and isa_init_ioport_range as the ISA devices are converted to the memory api. [avi: use memory_region_size()] Signed-off-by: Richard Henderson <rth@twiddle.net> Signed-off-by: Avi Kivity <avi@redhat.com>