MIPS: Octeon: Replace spinlock with raw_spinlocks in dma-octeon.c.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/973/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>