[POWERPC] Linkstation / kurobox support

Support for the Kurobox(HG)/LinkStation-I NAS systems by Buffalo
Technology, should be also applicable to the PPC TeraStation family.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>