The upcoming mt7988 has different temperature coefficients so we
cannot use constants in the functions lvts_golden_temp_init,
lvts_golden_temp_init and lvts_raw_to_temp anymore.

Add a field in the lvts_ctrl pointing to the lvts_data which now
contains the soc-specific temperature coefficents.

To make the code better readable, rename static int coeff_b to
golden_temp_offset, COEFF_A to temp_factor and COEFF_B to temp_offset.
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20230922055020.6436-4-linux@fw-web.de