iio: adc: rockchip_saradc: Use dev_err_probe

Use dev_err_probe instead of dev_err in probe function,
which simplifies code a little bit and prints the error
code.

Signed-off-by: Shreeya Patel <shreeya.patel@collabora.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20230603185340.13838-7-shreeya.patel@collabora.com


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