fw: Build with tkey-libs

Build firmware, testfw and testapp using tkey-libs:

  https://github.com/tillitis/tkey-libs

In an effort not to have more or less identical code maintained in two
places, use tkey-libs when developing firmware, testfw and the
firmware testapp, too.

You can place the Git directory directly under hw/application_fpga
and then an ordinary make should work.

Or build with:

  make LIBDIR=/path/to/tkey-libs

Co-authored-by: Mikael Ågren <mikael@tillitis.se>

hw/application_fpga/fw/tk1/blake2s/blake2s.h

@@ -4,7 +4,8 @@
 #ifndef BLAKE2S_H
 #define BLAKE2S_H
 
-#include "../types.h"
+#include <stdint.h>
+#include <stddef.h>
 
 // state context
 typedef struct {