Use a command group 'linuxgpiod' with subcommands instead of individual
commands with 'linuxgpiod_' prefix.
The old commands are still available for backward compatibility but
marked as deprecated.
Change-Id: Iad9b330363f81128ab1ec1cbc498df28ba2ca152
Signed-off-by: Marc Schink <dev@zapb.de>
Reviewed-on: http://openocd.zylin.com/6400
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>