[SSB]: Use ioreadX() and iowriteX() for PCI.

On a PCI bus use ioreadX() and iowriteX().
We map the I/O space with pci_iomap(), so we must use the correct
accessor functions, too.
readX() and writeX() are not guaranteed to accept the cookie returned
from pci_iomap() (though, it currently works on most architectures).

Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>