net/ipn3ke: fix accessing variable before null check
net/ipn3ke: fix accessing variable before null check

Check input argument "rte_eth_dev *ethdev", to be sure variable is not
NULL before operating on it.

Coverity issue: 337922
Fixes: 70d6b7f550f4 ("net/ipn3ke: add representor")
Cc: stable@dpdk.org

Signed-off-by: Andy Pei <495968cb2b3cf2ab5bd53dc54ba9a3450dc45709@intel.com>
Acked-by: Rosen Xu <8f603db01337dbfe2ce4743ebc0cdbcec6fa456f@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk