Add a few missing trap codes.

[ralf@linux-mips.org: Drop removal of exception codes.  I don't care what
the incomplete architecture spec says; it can't change existing hardware
and VCEI is supported indeed.]
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: kvm@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/11890/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>