Add the support for RDC R8610 Northbridge

Add the support for RDC R8610 Northbridge

So far the it just setups the internal resource management for coreboot and
detects the memory size.

Change-Id: I8506390fa6656abfa40d92b8f6ede9b91fe98680
Signed-off-by: Rudolf Marek <r.marek@assembler.cz>
Reviewed-on: http://review.coreboot.org/807
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>