thermal: trip: Get rid of thermal_zone_get_num_trips()

The only existing caller of thermal_zone_get_num_trips(), which is
rcar_gen3_thermal_probe(), uses this function to put the number of
trip points into a kernel log message, but this information is also
available from the thermal sysfs interface.

For this reason, remove the thermal_zone_get_num_trips() call from
rcar_gen3_thermal_probe() and drop the former altogether.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Link: https://patch.msgid.link/2636988.Lt9SDvczpP@rjwysocki.net