ethdev: add API to retrieve queue information

ethdev: add API to retrieve queue information

Add the ability for the upper layer to query RX/TX queue information.
Add into rte_eth_dev_info new fields to represent information about
RX/TX descriptors min/max/alig nnumbers per queue for the device.

Add new structures:
struct rte_eth_rxq_info
struct rte_eth_txq_info

new functions:
rte_eth_rx_queue_info_get
rte_eth_tx_queue_info_get

into rte_etdev API.

Left extra free space in the queue info structures,
so extra fields could be added later without ABI breakage.

Add new fields:
rx_desc_lim
tx_desc_lim
into rte_eth_dev_info.

Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Acked-by: Remy Horton <remy.horton@intel.com>