thermal/core: Remove THERMAL_TRIPS_NONE test

The last site calling the thermal_zone_bind_cooling_device() function
with the THERMAL_TRIPS_NONE parameter was removed.

We can get rid of this test as no user of this function is calling
this function with this parameter.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Thara Gopinath <thara.gopinath@linaro.org>
Link: https://lore.kernel.org/r/20201214233811.485669-5-daniel.lezcano@linaro.org