i82801gx: Don't set I/O base address to static value

i82801gx: Don't set I/O base address to static value

Doing it this way will break all subsequent smbus calls, because
the smbus code still uses res->base, which points to the old base
address. Fix this by allocating a proper resource.

Change-Id: I0f3d8fba5f8e2db7fe4ca991ef2c345aff436ea4
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Reviewed-on: http://review.coreboot.org/325
Reviewed-by: Rudolf Marek <r.marek@assembler.cz>
Tested-by: build bot (Jenkins)