net/af_packet: fix check of file descriptors
net/af_packet: fix check of file descriptors

Zero is a valid fd. It will fail to check the fd if the fd is zero.

Fixes: 527740ccfaec ("af_packet: fix some leaks")
Cc: stable@dpdk.org

Signed-off-by: Yunjian Wang <9985a735d5d5f80ef648228b285228d6eb6eaf45@huawei.com>
Reviewed-by: Ferruh Yigit <ba8734c3c506d2e3557bd4ac8fdaccd25bdb9aa7@intel.com>

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