MIPS: Netlogic: print cpumask with cpumask_scnprintf

Use standard function to print cpumask. Also fixup the name of the
variable used and make it static.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
Patchwork: http://patchwork.linux-mips.org/patch/5024/
Acked-by: John Crispin <blogic@openwrt.org>