ethdev: convert Tx offloads to Tx queue config
ethdev: convert Tx offloads to Tx queue config

Tx offload will be converted to txq_flags automatically during
rte_eth_dev_info_get and rte_eth_tx_queue_info_get. So PMD can
clean the code to get rid of txq_flags at all while keep old APP
not be impacted.

Signed-off-by: Qi Zhang <9e9e58ffa71a29bb7b87766b362515be648fcbe0@intel.com>
Tested-by: Andrew Rybchenko <ac94ab2a8fe9a9a087f6e24dcbc16626b52c07e8@solarflare.com>
Acked-by: Konstantin Ananyev <cbd5212b59ab42a210d72992d23a3aa17cfd3eaf@intel.com>

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