Use a command group 'sysfsgpio' with subcommands instead of individual
commands with 'sysfsgpio_' prefix.
The old commands are still available for backward compatibility but
marked as deprecated.
Change-Id: I103d8d9b0e3169a916d944a999579746f6f6a59c
Signed-off-by: Marc Schink <dev@zapb.de>
Reviewed-on: http://openocd.zylin.com/6402
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>