eventdev/eth_rx: add queue stats API

eventdev/eth_rx: add queue stats API

This patch adds new api ``rte_event_eth_rx_adapter_queue_stats_get`` to
retrieve queue stats. The queue stats are in the format
``struct rte_event_eth_rx_adapter_queue_stats``.

For resetting the queue stats,
``rte_event_eth_rx_adapter_queue_stats_reset`` api is added.

The adapter stats_get and stats_reset apis are also updated to
handle queue level event buffer use case.

Signed-off-by: Naga Harish K S V <s.v.naga.harish.k@intel.com>
Acked-by: Jay Jayatheerthan <jay.jayatheerthan@intel.com>