ACPI: thermal: Merge trip initialization functions

In order to reduce code duplicationeve further, merge
acpi_thermal_init_passive/active_trip() into one function called
acpi_thermal_init_trip() that will be used for initializing both
the passive and active trip points.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>