greybus: gpio: fix memory leaks at init and exit

Fix three related memory leaks in the init an exit callbacks, where the
gpio-lines array was never freed at all and the controller data wasn't
freed in the init error path.

Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>