MIPS: Netlogic: Get coremask from FUSE register

Use the FUSE register to get the list of active cores in the CPU
instead of using the CPU reset register, this is the recommended
method.

Also add code to mask the coremask with the default number of cores
for each processor series.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/6275/