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/expr.c

@@ -1131,7 +1131,6 @@ static int expr_compare_type(enum expr_type t1, enum expr_type t2)
 	default:
 		return -1;
 	}
-	printf("[%dgt%d?]", t1, t2);
 	return 0;
 }