cc2520: move to gpio descriptors

cc2520 supports both probing from static platform_data and
from devicetree, but there have never been any definitions
of the platform data in the mainline kernel, so it's safe
to assume that only the DT path is used.

After folding cc2520_platform_data into the driver itself,
the GPIO handling can be simplified by moving to the modern
gpiod interface.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20230126161658.2983292-1-arnd@kernel.org


Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>