MIPS: OCTEON: Add OCTEON3 to __get_cpu_type

Otherwise __builtin_unreachable might be called.

Signed-off-by: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Cc: David Daney <ddaney.cavm@gmail.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: kvm@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/7014/


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