staging:iio:ad7606: Use GPIO descriptor API

Convert the ad7606 driver away from the deprecated legacy GPIO API and use
the new GPIO descriptor API.

This also means that the platform data struct is now empty and can be
removed.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
3 files changed