ARM: Orion5x: ts78xx: Add IOMEM for virtual addresses.

Also convert logical or to + for register offsets from base
addresses. This fixes a number of warnings currently seen in
linux-next:

warning: passing argument 2 of '__raw_writeb' makes pointer from
interger without cast.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>