Check returned value after strtok()
CID 355674 (#1 of 1): Dereference null return value (NULL_RETURNS)
4. dereference: Dereferencing a pointer that might be NULL s when
calling inet_pton
Fixes: 103809d032cd ("app/test-fib: add test application for FIB")
Cc: stable@dpdk.org
Signed-off-by: Vladimir Medvedkin <vladimir.medvedkin@intel.com>