sh: Handle ioport_map() cases for >= P1SEG addresses.

This fixes up the case where certain drivers already do their own
remapping and subsequently attempt to use the PIO calls for I/O. In this
case there is no additional remapping that needs to be done, and the
address can be casted in to the cookie directly.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>