iio: adc: ti-adc128s052: Switch to use spi_get_device_match_data()

The spi_get_device_match_data() helps to get driver data from the
firmware node or SPI ID table. Use it instead of open coding.

While at it, switch ID tables to provide an acrual pointers to
the configuration data.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230102173450.29882-2-andriy.shevchenko@linux.intel.com


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