In a future patch HAS_IOPORT=n will disable inb()/outb() and friends at
compile time. We thus need to add HAS_IOPORT as dependency for those
drivers using them. In the bochs driver there is optional MMIO support
detected at runtime, warn if this isn't taken when HAS_IOPORT is not
defined.
There is also a direct and hard coded use in cirrus.c which according to
the comment is only necessary during resume. Let's just skip this as
for example s390 which doesn't have I/O port support also doesen't
support suspend/resume.