ARM: mv78xx0: use fixed pci i/o mapping

Move mv78xx0 PCI to fixed i/o mapping and remove io.h. This changes the PCI
bus addresses from the cpu address to 0 based. It appears that there is
translation h/w for this, but its untested.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>