sh: Support PCI IO access of SH7780 base boards.

The IO access of PCI is not supported in R7780RP and the MS7780SE
board now. The support of the IO access mode of e100 and a lot of IDE
chips becomes possible by fixing the code.

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>