sandbox: drop unused return

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/sandbox/cpu/start.c b/arch/sandbox/cpu/start.c
index 685793e..a429e29 100644
--- a/arch/sandbox/cpu/start.c
+++ b/arch/sandbox/cpu/start.c
@@ -28,6 +28,4 @@
 	 * never return.
 	 */
 	board_init_f(0);
-
-	return 0;
 }