This is a minor patch to get things setup so consoles can
work earlier.  (No change to consoles here, I just split this
out to make the diff easier to read.)

(io_port_init): New function, same old code to setup ia64_iobase
and legacy IO port space.
(setup_arch): Call io_port_init() and machvec_init() as early as
possible so consoles can work earlier.