fix a format string directives in queue_seqset()

Coverity pointed out that a format string used inappropriate
format string directives for variables of type size_t.

Change-Id: I889019aad963932fdc032421e60a72c809a93bca
Related: CID#135197
diff --git a/gtp/queue.c b/gtp/queue.c
index 82cd7b4..ebeebe6 100644
--- a/gtp/queue.c
+++ b/gtp/queue.c
@@ -79,7 +79,7 @@
 	if (QUEUE_DEBUG)
 		printf("Begin queue_seqset seq = %d\n", (int)seq);
 	if (QUEUE_DEBUG)
-		printf("SIZEOF PEER %d, *PEER %d\n", sizeof(peer),
+		printf("SIZEOF PEER %zu, *PEER %zu\n", sizeof(peer),
 		       sizeof(*peer));
 
 	qmsg->seq = seq;