BUG/MINOR: quic: Wrong status returned by qc_pkt_decrypt()

This bug came with this big commit:
     "MEDIUM: quic: xprt traces rework"

This is the <ret> variable value which must be returned by most of the xprt functions.
This leaded packets which could not be decrypted to be parsed, with weird frames
to be parsed as found by Tristan in GH #1808.

To be backported where the commit above was backported.

src/xprt_quic.c

@@ -1453,7 +1453,7 @@ static int qc_pkt_decrypt(struct quic_rx_packet *pkt, struct quic_enc_level *qel
 	ret = 1;
  leave:
 	TRACE_LEAVE(QUIC_EV_CONN_RXPKT, qc);
-	return 1;
+	return ret;
 }