Invalid pattern mask error with Intel i40e driver and possible fix

[Shangwei-Li]

Hi,
I would like to report a bug found in #12, which is related to Intel i40e driver, and a possible fix.
I am using Intel X722 10GbE card with the dpdk backend, and running switchML helloworld will throw an error at the function switchml:: InsertFlowRule():
F0721 16:21:16.853484 108 dpdk_master_thread_utils.inc:154] Flow rule can't be added: 13Invalid pattern mask.

I believe this is a compatibility issue with NICs that use Intel i40e driver. So I commented out this line in dev_root/client_lib/src/backends/dpdk/dpdk_master_thread_utils.inc:
134 ip_mask.hdr.next_proto_id = 0xFF;
After that, I can run switchML helloworld and allreduce benchmark with multi-thread. If all incoming packets are UDP, this line should not be necessary and maybe it should be removed for compatibility.