MIPS: Netlogic: Enable SUE bit in cores

Enable Speculative Unmap Enable bit, which will enable speculative L2
cache requests for unmapped memory. This should give better performance
for kernel code/data which is in KSEG0

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
Patchwork: http://patchwork.linux-mips.org/patch/4461
Signed-off-by: John Crispin <blogic@openwrt.org>