staging: greybus: arche-apb-ctrl.c: Switch to the gpio descriptor interface

Use the gpiod interface instead of the deprecated old non-descriptor
interface while continuing to ignore gpio flags from device tree in
functions "deassert_reset()" and "assert_reset()" for now.

Reviewed-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Nishad Kamdar <nishadkamdar@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>