Initialize ret

Without this debug builds will fail.

BUG=none
TEST=USE=debug emerge-sarien depthcharge libpayload chromeos-bootimage
BRANCH=none

Change-Id: Iff182a116e89a8144a2102b288ea87fa75ff8885
Signed-off-by: Mathew King <mathewk@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1553920
Reviewed-by: Raul E Rangel <rrangel@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
diff --git a/firmware/lib/vboot_ui_menu.c b/firmware/lib/vboot_ui_menu.c
index 6c65f1c..505a4ca 100644
--- a/firmware/lib/vboot_ui_menu.c
+++ b/firmware/lib/vboot_ui_menu.c
@@ -804,6 +804,7 @@
 				  "user pressed key '%c': Boot alternative "
 				  "firmware\n", key);
 			vb2_try_alt_fw(ctx, altfw_allowed, key - '0');
+			ret = VBERROR_KEEP_LOOPING;
 			break;
 		default:
 			ret = vb2_handle_menu_input(ctx, key, 0);