obmc-console: Clean up invalid sign comparisons

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: I83fae6857620ca2913952bea597c1299dd962620
diff --git a/test/ringbuffer-test-utils.c b/test/ringbuffer-test-utils.c
index c489f9d..bbe688a 100644
--- a/test/ringbuffer-test-utils.c
+++ b/test/ringbuffer-test-utils.c
@@ -69,7 +69,8 @@
 void ringbuffer_dump(struct ringbuffer *rb)
 {
 	struct ringbuffer_consumer *rbc;
-	int i, j;
+	size_t i;
+	int j;
 
 	printf("---- ringbuffer (%d consumer%s)\n", rb->n_consumers,
 			rb->n_consumers == 1 ? "" : "s");