iio: dac: ad8460: Stop using iio_device_claim_direct_scoped()

iio: dac: ad8460: Stop using iio_device_claim_direct_scoped()

This complex cleanup.h use case of conditional guards has proved
to be more trouble that it is worth in terms of false positive compiler
warnings and hard to read code.

Move directly to the new claim/release_direct() that allow sparse
to check for unbalanced context.

Cc: Mariel Tinaco <Mariel.Tinaco@analog.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://patch.msgid.link/20250209180624.701140-24-jic23@kernel.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>