staging: iio: Augment TODO file with GPIO work item

To make sure that these drivers do not leave staging before they
are properly converted to use the new GPIO descriptor API,
augment the TODO file with this work item.
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>
Acked-by: NJonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/iio/TODO

-2016 10/09
+2018-04-15
+
+All affected drivers:
+Convert all uses of the old GPIO API from <linux/gpio.h> to the
+GPIO descriptor API in <linux/gpio/consumer.h> and look up GPIO
+lines from device tree, ACPI or board files, board files should
+use <linux/gpio/machine.h>.
+
 
 ADI Drivers:
 CC the device-drivers-devel@blackfin.uclinux.org mailing list when