iio: temperature: ltc2983: rename ltc2983_parse_dt()

Rename ltc2983_parse_dt() to ltc2983_parse_fw() as there's no explicit
dependency on devicetree. No functional change intended...

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240222-ltc2983-misc-improv-v1-2-cf7d4457e98c@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>