thermal/drivers/mediatek/lvts: Add support for ATP mode

thermal/drivers/mediatek/lvts: Add support for ATP mode

MT8196/MT6991 uses ATP (Abnormal Temperature Prevention) mode to detect
abnormal temperature conditions, which involves reading temperature data
from a dedicated set of registers separate from the ones used for
immediate and filtered modes.

Add support for ATP mode and its relative registers to ensure accurate
temperature readings and proper thermal management on MT8196/MT6991
devices.

While at it, convert mode defines to enum.

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-v5-5-6db7eb903fb7@collabora.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>