eficonfig: CTRL+S to save the boot order

The change boot order menu in eficonfig can have at most INT_MAX lines
and it is troublesome to scroll down to the "Save" entry.

This commit assigns CTRL+S to save the boot order.

Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>
Acked-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/common/menu.c b/common/menu.c
index cdcdbb2..9451417 100644
--- a/common/menu.c
+++ b/common/menu.c
@@ -503,6 +503,9 @@
 	case CTL_CH('n'):
 		key = BKEY_DOWN;
 		break;
+	case CTL_CH('s'):
+		key = BKEY_SAVE;
+		break;
 	case '+':
 		key = BKEY_PLUS;
 		break;