MIPS: Netlogic: Add topology.h for XLP family

Add mach-netlogic/topology.h which contains XLP cpu number to core and
node mapping.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/6271/