The driver ftdi defines the command 'ftdi serial' to specify the
serial string of the adapter.
Remove and deprecate the driver command, and use 'adapter serial'.
Change-Id: Ia5b1f325b9fab8f58b5ea70f8b807e50b148b939
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/6651
Tested-by: jenkins