kconfig: fix missing '# end of' for empty menu

Currently, "# end of ..." is inserted when the menu goes back to its
parent.

Hence, an empty menu:

  menu "Foo"
  endmenu

... ends up with unbalanced menu comments, like this:

  #
  # Foo
  #

Let's close the menu comments properly:

  #
  # Foo
  #
  # end of Foo
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/kconfig/confdata.c

@@ -903,19 +903,20 @@ int conf_write(const char *name)
 			menu = menu->list;
 			continue;
 		}
-		if (menu->next)
-			menu = menu->next;
-		else while ((menu = menu->parent)) {
-			if (!menu->sym && menu_is_visible(menu) &&
-			    menu != &rootmenu) {
-				str = menu_get_prompt(menu);
-				fprintf(out, "# end of %s\n", str);
+
+end_check:
+		if (!menu->sym && menu_is_visible(menu) && menu != &rootmenu &&
+		    menu->prompt->type == P_MENU) {
+			fprintf(out, "# end of %s\n", menu_get_prompt(menu));
 			need_newline = true;
 		}
+
 		if (menu->next) {
 			menu = menu->next;
-				break;
-			}
+		} else {
+			menu = menu->parent;
+			if (menu)
+				goto end_check;
 		}
 	}
 	fclose(out);