iio: adc: Remove dev_err_probe() if error is -ENOMEM

iio: adc: Remove dev_err_probe() if error is -ENOMEM

The dev_err_probe() doesn't do anything when the error is '-ENOMEM'.
Therefore, remove the useless call to dev_err_probe(), and just return the
value instead.

Signed-off-by: Xichao Zhao <zhao.xichao@vivo.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com> # meson_saradc
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Link: https://patch.msgid.link/20250821080723.525379-3-zhao.xichao@vivo.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>