kconfig: nuke LKC_DIRECT_LINK cruft

This interface is not (and has never been ?) used by any frontend, just get rid
of it.

Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>
diff --git a/scripts/kconfig/nconf.c b/scripts/kconfig/nconf.c
index 488dd74..da9f5c4 100644
--- a/scripts/kconfig/nconf.c
+++ b/scripts/kconfig/nconf.c
@@ -7,7 +7,7 @@
  */
 #define _GNU_SOURCE
 #include <string.h>
-#define LKC_DIRECT_LINK
+
 #include "lkc.h"
 #include "nconf.h"
 #include <ctype.h>