iio: adc: ad7606: Sort includes in alphabetical order

Some of the includes were not in alphabetical order, this commit fixes
it.

Signed-off-by: Guillaume Stols <gstols@baylibre.com>
Link: https://patch.msgid.link/20241004-ad7606_add_iio_backend_support-v3-5-38757012ce82@baylibre.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>