event/cnxk: fix Tx adapter enqueue return for CN10K

The `rte_event_eth_tx_adapter_enqueue()` function expects driver layer
to return the total number of events successfully transmitted.
Fix cn10k driver returning the number of packets transmitted in a
event vector instead of number of events.

Fixes: 761a321 ("event/cnxk: support vectorized Tx event fast path")
Cc: stable@dpdk.org

Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>

drivers/event/cnxk/cn10k_worker.h

@@ -651,7 +651,7 @@ cn10k_sso_hws_event_tx(struct cn10k_sso_hws *ws, struct rte_event *ev,
 		}
 		rte_mempool_put(rte_mempool_from_obj(ev->vec), ev->vec);
 		rte_prefetch0(ws);
-		return (meta & 0xFFFF);
+		return 1;
 	}
 
 	m = ev->mbuf;