iio: potentiometer: ds1803: Convert enum->pointer for data in the ID table

Convert enum->pointer for data in the ID table, so that
device_get_match_data() can do match against OF/ACPI/I2C tables, once i2c
bus type match support added to it.

Replace enum->struct *ds1803_cfg for data in the ID table and simplify
ds1803_probe() by replacing device_get_match_data() with
i2c_get_match_data().

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230812144106.163355-1-biju.das.jz@bp.renesas.com


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