BUILD: fix compilation error with DEBUG_FULL

Recent changes in structures broke the compilation when using DEBUG_FULL.
Let's update apply the changes also to the variables used in DPRINTF calls.
diff --git a/src/dumpstats.c b/src/dumpstats.c
index 48419c1..37dfcbc 100644
--- a/src/dumpstats.c
+++ b/src/dumpstats.c
@@ -1614,7 +1614,7 @@
  out:
 	DPRINTF(stderr, "%s@%d: st=%d, rqf=%x, rpf=%x, rqh=%d, rqs=%d, rh=%d, rs=%d\n",
 		__FUNCTION__, __LINE__,
-		si->state, req->flags, res->flags, req->i, req->o, res->i, res->o);
+		si->state, req->flags, res->flags, req->buf.i, req->buf.o, res->buf.i, res->buf.o);
 
 	if (unlikely(si->state == SI_ST_DIS || si->state == SI_ST_CLO)) {
 		/* check that we have released everything then unregister */