thermal/drivers/mediatek/lvts: Add lvts_temp_to_raw variant

thermal/drivers/mediatek/lvts: Add lvts_temp_to_raw variant

MT8196/MT6991 require a different version of lvts_temp_to_raw(),
specifically the multiplicative inverse of the existing implementation.
Introduce a variant of the function with inverted calculation logic to
match this requirement.

This ensures accurate raw value generation for temperature
thresholds, avoiding spurious thermal interrupts or unintended hardware
resets on MT8196/MT6991.

Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Fei Shao <fshao@chromium.org>
Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: Frank Wunderlich <frank-w@public-files.de>
Signed-off-by: Laura Nao <laura.nao@collabora.com>
Link: https://patch.msgid.link/20251125-mt8196-lvts-v4-v5-4-6db7eb903fb7@collabora.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>