gpio: TODO: add an item to track reworking the sysfs interface

It seems there really exists the need for a simple sysfs interface that
can be easily used from minimal initramfs images that don't contain much
more than busybox. However the current interface poses a challenge to
the removal of global GPIO numberspace. Add an item that tracks
extending the existing ABI with a per-chip export/unexport attribute
pair.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250321-gpio-todo-updates-v1-6-7b38f07110ee@linaro.org


Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>