MINOR: quic: Stop emptying the RX buffer asap.

When a packet is present in the RX buffer at the first place
but without a null reference counter, there is no need to continue
to try to empty the buffer, it is sure the next packet will not
be at the first place!
diff --git a/include/haproxy/xprt_quic.h b/include/haproxy/xprt_quic.h
index b731da2..13de0f1 100644
--- a/include/haproxy/xprt_quic.h
+++ b/include/haproxy/xprt_quic.h
@@ -1083,11 +1083,12 @@
 			break;
 		}
 
-		if (!HA_ATOMIC_LOAD(&pkt->refcnt)) {
-			b_del(&qc->rx.buf, pkt->raw_len);
-			LIST_DELETE(&pkt->qc_rx_pkt_list);
-			pool_free(pool_head_quic_rx_packet, pkt);
-		}
+		if (HA_ATOMIC_LOAD(&pkt->refcnt))
+			break;
+
+		b_del(&qc->rx.buf, pkt->raw_len);
+		LIST_DELETE(&pkt->qc_rx_pkt_list);
+		pool_free(pool_head_quic_rx_packet, pkt);
 	}
 }