MIPS: Octeon: Use write_{un,}lock_irq{restore,save} to set irq affinity

Since the locks are used from interrupt context we need the
irqsave/irqrestore versions of the locking functions.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>