contrail-vrouter-dpdk: fail with XL710 (i40e dpdk driver), "Error getting RSS RETA info"

We use Intel XL710 40GbE. It's handled by i40e driver in DPDK.
contrail-vrouter-dpdk fails to create vhost0 interface, following error observed in logs:

2017-06-01 13:35:49,921 PMD: i40e_pf_config_rss(): Max of contiguous 8 PF queues are configured
2017-06-01 13:35:49,966 VROUTER: Error getting RSS RETA info: Unknown error -22 (-22)
2017-06-01 13:35:49,966 VROUTER: error initializing ethdev 0 RSS: Invalid argument (22)
2017-06-01 13:35:49,966 VROUTER: Error getting RSS RETA info: Unknown error -22 (-22)
2017-06-01 13:35:49,966 VROUTER: Deleting vif 0 eth device

Root cause found:
1. Intel xl710 NIC supports 512 rss entries per PF in redirection table (ref. http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/xl710-10-40-controller-datasheet.pdf).
2. This value (512) is set to internal structure in i40e drv, and propagated to contrail-vrouter (via rte_eth_dev_info_get called from dpdk_ethdev_info_update).
3. Contrail vrouter takes this number and makes this thing with it:
    ethdev->ethdev_reta_size = RTE_MIN(dev_info.reta_size, VR_DPDK_MAX_RETA_SIZE);
thus the number becomes 128 (value of "VR_DPDK_MAX_RETA_SIZE");
4. Contrail calls i40e driver function (via rte_eth_dev_rss_reta_query) giving 128 to it as a reta_size;
5. i40e driver fails in `i40e_dev_rss_reta_query` since it expects to get exactly same value as saved in internal structure, i.e. 512.

Suggested fix:
Increase value VR_DPDK_MAX_RETA_SIZE, set it to 512.