gpio: TODO: add an item to track the conversion to the new value setters

Add an item tracking the treewide conversion of GPIO drivers to using
the new line value setter callbacks in struct gpio_chip instead of the
old ones that don't allow drivers to signal failures to callers.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250321-gpio-todo-updates-v1-5-7b38f07110ee@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Author: Bartosz Golaszewski

drivers/gpio/TODO

@@ -161,3 +161,15 @@ A small number of drivers have been converted (pl061, tegra186, msm,
 amd, apple), and can be used as examples of how to proceed with this
 conversion. Note that drivers using the generic irqchip framework
 cannot be converted yet, but watch this space!
+
+-------------------------------------------------------------------------------
+
+Convert all GPIO chips to using the new, value returning line setters
+
+struct gpio_chip's set() and set_multiple() callbacks are now deprecated. They
+return void and thus do not allow drivers to indicate failure to set the line
+value back to the caller.
+
+We've now added new variants - set_rv() and set_multiple_rv() that return an
+integer. Let's convert all GPIO drivers treewide to use the new callbacks,
+remove the old ones and finally rename the new ones back to the old names.