iio: adc: rzg2l_adc: Convert dev_err() to dev_err_probe()

Convert all occurrences of dev_err() in the probe path to dev_err_probe().
This improves readability and simplifies the code.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://patch.msgid.link/20241206111337.726244-3-claudiu.beznea.uj@bp.renesas.com


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