thermal: Simplify or eliminate unnecessary set_mode() methods

Setting polling_delay is now done at thermal_core level (by not polling
DISABLED devices), so no need to repeat this code.

int340x: Checking for an impossible enum value is unnecessary.
acpi/thermal: It only prints debug messages.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
[for acerhdf]
Acked-by: Peter Kaestle <peter@piie.net>
Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20200629122925.21729-11-andrzej.p@collabora.com