fw: Import tkey-libs fw-2

This is an import of the fw-2 tag of tkey-libs.

We import the entire tkey-libs repo minus dot files into the
tillitis-key1 repo to make it very simple not to make mistakes
regarding which firmware tag depends on which tkey-libs tag,
especially considering locking down with NVCM.

Please see README for information about developing with another
tkey-libs or how to import future tkey-libs.

Since tkey-libs is now a part of the repo we also add tkey-libs to the
clean_fw target.

hw/application_fpga/tkey-libs/libcommon/blake2s.c

@@ -0,0 +1,14 @@
+// SPDX-FileCopyrightText: 2023 Tillitis AB <tillitis.se>
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <stdint.h>
+#include <tkey/blake2s.h>
+#include <tkey/tk1_mem.h>
+
+int blake2s(void *out, unsigned long outlen, const void *key,
+	    unsigned long keylen, const void *in, unsigned long inlen,
+	    blake2s_ctx *ctx)
+{
+	// Not implemented.
+	return -1;
+}