MINOR: quic: Trace fix in qc_release_frm()

This wrong trace came with this commit:
  "BUG/MINOR: quic: Possible crashes when dereferencing ->pkt quic_frame struct member"
In qc_release_frm() we mark frames as acked. Nothing to see with references
to frames.

Thank you to Willy for having caught this one.

Must be backported to 2.6 as these traces arrived with a bug fix to be backported
to 2.6.
diff --git a/src/xprt_quic.c b/src/xprt_quic.c
index baee8e2..9c42e52 100644
--- a/src/xprt_quic.c
+++ b/src/xprt_quic.c
@@ -1510,7 +1510,7 @@
 		}
 		else {
 			/* XXX TODO: what must be done for such a frame */
-			TRACE_DEVEL("remove frame reference for unsent frame",
+			TRACE_DEVEL("mark frame as acked for unsent frame",
 			            QUIC_EV_CONN_PRSAFRM, qc, f);
 		}
 		f->flags |= QUIC_FL_TX_FRAME_ACKED;