staging: iio: resolver: ad2s1210: fix use before initialization

This fixes a use before initialization in ad2s1210_probe(). The
ad2s1210_setup_gpios() function uses st->sdev but it was being called
before this field was initialized.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20230929-ad2s1210-mainline-v3-2-fa4364281745@baylibre.com


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