ft2232: ft2232_channel option added

With this option a different channel of the ft2232 chip can be selected using
a previously existing layout. It was made for a partner called Salvador
Tropea.

Change-Id: Ia0dedb2f50e232d089e73788735edc8f47ee23e6
Signed-off-by: Rodrigo Melo <rmelo@inti.gob.ar>
Reviewed-on: http://openocd.zylin.com/1095
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>
interface: opendous_ftdi config file added

This config file add support to the opendous cable based on the chip ft2232H,
using the ft2232 interface driver.

Change-Id: I8171a0c475af8d61e081844ee86466a392138fb0
Signed-off-by: Rodrigo Melo <rmelo@inti.gob.ar>
Reviewed-on: http://openocd.zylin.com/1096
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>