[legal] Add some missing FILE_LICENCE declarations

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/hci/commands/gdbstub_cmd.c

@@ -16,6 +16,8 @@
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+FILE_LICENCE ( GPL2_OR_LATER );
+
 #include <stdio.h>
 #include <errno.h>
 #include <assert.h>