greybus: arche-platform: Export gpio (reset & sys_boot) to user

In order to allow user to flash the firmware to,

SVC:
user need to assert the reset first, set sysboot pin and
deassert reset. And then issue a flashing command.

And APB:
User need to assert the reset first, and then issue flashing
command.

So this patch exports the gpio's to user.

Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>