obmc-console: Clean up invalid sign comparisons

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: I83fae6857620ca2913952bea597c1299dd962620
diff --git a/console-socket.c b/console-socket.c
index b0cd452..461f151 100644
--- a/console-socket.c
+++ b/console-socket.c
@@ -43,7 +43,7 @@
 	if (rc < 0)
 		return rc;
 
-	if (rc > (sizeof(addr->sun_path) - 1)) {
+	if ((size_t)rc > (sizeof(addr->sun_path) - 1)) {
 		errno = 0;
 		return -1;
 	}