Use a command group 'ftdi' with subcommands instead of individual
commands with 'ftdi_' prefix.
The old commands are still available for backward compatibility but
marked as deprecated.
Change-Id: I93a0ae7070226cd2fdea566effeb14a141269de8
Signed-off-by: Marc Schink <dev@zapb.de>
Reviewed-on: http://openocd.zylin.com/6332
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>