iio: adc: ad7606: using claim_direct_scoped for code simplification

iio: adc: ad7606: using claim_direct_scoped for code simplification

Using iio_device_claim_direct_scoped instead of calling `iio_device
_claim_direct_modeand later callingiio_device_release_direct_mode`

This should make code cleaner and error handling easier

Co-authored-by: Lais Nuto <laisnuto@usp.br>
Signed-off-by: Lais Nuto <laisnuto@usp.br>
Signed-off-by: Jorge Harrisonn <jorge.harrisonn@usp.br>
Link: https://lore.kernel.org/r/20240501215724.26655-2-jorge.harrisonn@usp.br
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>