mlx4: restore conditional call to napi_complete_done()

After commit 1a288172 ("mlx4: use napi_complete_done()") we ended up
calling napi_complete_done() in the case NAPI poll consumed all its
budget.

This added extra interrupt pressure, this patch restores proper
behavior.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: 1a288172 ("mlx4: use napi_complete_done()")
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/en_rx.c

@@ -910,14 +910,15 @@ int mlx4_en_poll_rx_cq(struct napi_struct *napi, int budget)
 		cpu_curr = smp_processor_id();
 		aff = irq_desc_get_irq_data(cq->irq_desc)->affinity;
 
-		if (unlikely(!cpumask_test_cpu(cpu_curr, aff))) {
+		if (likely(cpumask_test_cpu(cpu_curr, aff)))
+			return budget;
+
 		/* Current cpu is not according to smp_irq_affinity -
 		 * probably affinity changed. need to stop this NAPI
 		 * poll, and restart it on the right CPU
 		 */
 		done = 0;
 	}
-	}
 	/* Done for now */
 	napi_complete_done(napi, done);
 	mlx4_en_arm_cq(priv, cq);