Net: e100, fix iomap mem accesses

Patch against netdev-2.6 follows.
--
writeX functions are not permitted on iomap-ped space change to iowriteX,
also pci_unmap pci_map-ped space on exit (instead of iounmap).

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: David S. Miller <davem@davemloft.net>