MIPS: Netlogic: add XLS6xx to FMN config

Add support for XLS6xx CPUs to the Fast Message Network (FMN)
configuration.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
Patchwork: http://patchwork.linux-mips.org/patch/4785/


Signed-off-by: John Crispin <blogic@openwrt.org>