usb: gadget: udc: atmel: check rc of devm_gpiod_get_optional()

devm_gpiod_get_optional() might still return an error code, esp.
EPROBE_DEFER. Return any errors.

Signed-off-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20220705131951.1388968-1-michael@walle.cc


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>