Assign RSS offload type with NIC supported values

[sippejw]

Description

As noted in issue #38, the RSS offload types is currently hardcoded and not all NICs support the set value. This PR takes the suggestion from @tbarbette and updates the assignment to a value provided by the NIC (dev_info.flow_type_rss_offloads).

Testing

I have only tested this on an Intel X710. If @thearossman can test this on the ConnectX-5 and any other hardware they have that would be great.

[thearossman]

Thank you for getting to this!!

Can you try this as a bitwise & on your system? It would be ideal to not enable all of the supported RSS types if we don't need them, since there could be a lot. I'm thinking bitwise & with the original mask:

(dpdk::ETH_RSS_IP | dpdk::ETH_RSS_TCP | dpdk::ETH_RSS_UDP) & dev_info.flow_type_rss_offloads

The IP, TCP, and UDP macros are composed of multiple sub-macros (http://doc.dpdk.org/api-22.03/rte__ethdev_8h_source.html), so these would capture most if not all of what you listed here: #38.

Others like RTE_ETH_RSS_L2_PAYLOAD would be useful to add when non-TCP/UDP protocols are supported.

The above works on the mlx5!