iio: adc: mt6577_auxadc: Simplify with dev_err_probe()

Use the dev_err_probe() helper to simplify error handling during probe.
This also handle scenario, when EDEFER is returned and useless error
is printed.

Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Suggested-by: Jonathan Cameron <jic23@kernel.org>
Link: https://lore.kernel.org/r/20230826035402.3512033-2-ruanjinjie@huawei.com


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