MINOR: quic: Useless test in quic_lstnr_dghdlr()

This statement is useless. This should fix CID 1469651 for GH #1546.
diff --git a/src/xprt_quic.c b/src/xprt_quic.c
index 11c5d32..bec37ac 100644
--- a/src/xprt_quic.c
+++ b/src/xprt_quic.c
@@ -5241,9 +5241,6 @@
 	int first_pkt = 1;
 
 	while ((dgram = MT_LIST_POP(&dghdlr->dgrams, typeof(dgram), mt_list))) {
-		if (!dgram)
-			goto err;
-
 		pos = dgram->buf;
 		end = pos + dgram->len;
 		do {