MIPS: Netlogic: Add cpu to node mapping for XLP9XX

XLP9XX has 20 cores per node, opposed to 8 on earlier XLP8XX.
Update code that calculates node id from cpu id to handle this.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/6283/