MIPS: OCTEON: irq: Check for null return on kzalloc allocation

The allocation of host_data is not null checked, leading to a null
pointer dereference if the allocation fails. Fix this by adding a null
check and return with -ENOMEM.

Fixes: 64b139f9 ("MIPS: OCTEON: irq: add CIB and other fixes")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: David Daney <david.daney@cavium.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: "Steven J. Hill" <Steven.Hill@cavium.com>
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # 4.0+
Patchwork: https://patchwork.linux-mips.org/patch/18658/


Signed-off-by: James Hogan <jhogan@kernel.org>