iio: proximity: sx_common: Unexport sx_common_get_raw_register_config()

sx_common_get_raw_register_config() is used in a single driver,
move it there.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20240903212922.3731221-3-andriy.shevchenko@linux.intel.com


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