thermal: of: Rename struct __thermal_trip to struct thermal_trip

This patch changes name of struct __thermal_trip to thermal_trip and moves
declaration of the latter to ./include/linux/thermal.h for better visibility.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
(cherry picked from commit ad9914ac3b1f5c12ef2cf1c58a6ddda306fb79d4)
Signed-off-by: Kevin Hilman <khilman@linaro.org>