MIPS: Fix build breakage if CONFIG_DEBUG_FS is enabled.

Caused by 38b7827f - no, cpu_local_* was
not unused.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Acked-by: David Daney <ddaney@caviumnetworks.com>