iio: adc: ti-adc109s102: drop ACPI_PTR() and CONFIG_ACPI guards

The complexity of config guards needed for ACPI_PTR() is not worthwhile
for the small amount of saved data. This example was doing it correctly
but I am proposing dropping this so as to reduce chance of cut and paste
where it is done wrong.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20231231183514.566609-25-jic23@kernel.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>