util/kconfig: Uprev to Linux 6.8's kconfig

Linux kconfig has its own implementation of KCONFIG_WERROR now, so use
that. This reduces our patch count by 2.

Change-Id: I4f5f1f552e96f8ef7a4c5c0ab2ab7e2b6d798ceb
Signed-off-by: Patrick Georgi <patrick@georgi.software>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/81223
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

util/kconfig/mnconf-common.c

@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include "expr.h"
+#include "list.h"
+#include "mnconf-common.h"
+
+int jump_key_char;
+
+int next_jump_key(int key)
+{
+	if (key < '1' || key > '9')
+		return '1';
+
+	key++;
+
+	if (key > '9')
+		key = '1';
+
+	return key;
+}
+
+int handle_search_keys(int key, size_t start, size_t end, void *_data)
+{
+	struct search_data *data = _data;
+	struct jump_key *pos;
+	int index = 0;
+
+	if (key < '1' || key > '9')
+		return 0;
+
+	list_for_each_entry(pos, data->head, entries) {
+		index = next_jump_key(index);
+
+		if (pos->offset < start)
+			continue;
+
+		if (pos->offset >= end)
+			break;
+
+		if (key == index) {
+			data->target = pos->target;
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+int get_jump_key_char(void)
+{
+	jump_key_char = next_jump_key(jump_key_char);
+
+	return jump_key_char;
+}