MIPS: OCTEON: Don't do acknowledge operations for level triggered irqs.

The acknowledge bits don't exist for level triggered irqs, so setting
them causes the simulator to terminate.

Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Leonid Rosenboim <lrosenboim@caviumnetworks.com>
Signed-off-by: Aleksey Makarov <aleksey.makarov@auriga.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8946/


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