ethdev: add MACsec event type

This commit adds a below event type:

- RTE_ETH_EVENT_MACSEC

This event will occur when the PN counter in a MACsec connection
reaches the exhaustion threshold.

Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>

lib/librte_ether/rte_ethdev.h

@@ -3188,6 +3188,7 @@ enum rte_eth_event_type {
 	RTE_ETH_EVENT_INTR_RESET,
 			/**< reset interrupt event, sent to VF on PF reset */
 	RTE_ETH_EVENT_VF_MBOX,  /**< message from the VF received by PF */
+	RTE_ETH_EVENT_MACSEC,   /**< MACsec offload related event */
 	RTE_ETH_EVENT_MAX       /**< max value of this enum */
 };