thermal/drivers/u8500: Remove the get_trend function

thermal/drivers/u8500: Remove the get_trend function

The get_trend function relies on the interrupt to set the raising or
dropping trend. However the interpolated temperature is already giving
the temperature information to the thermal framework which is able to
deduce the trend.

Remove the trend code.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20220616202537.303655-3-daniel.lezcano@linaro.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>