build fix: ft2232

fix build with-ftd2xx-lib

Change-Id: I4a9b5d204c29b7a0714a59494b2b5f959c73f99b
Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Reviewed-on: http://openocd.zylin.com/1359
Tested-by: jenkins
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>