As the active cooling devices can have multiple cooling states,
we may want only several cooling states for a certain trip point,
and other cooling states for other active trip points.

To do this, we should be able to describe the cooling device
behavior for a certain trip point, rather than for the entire thermal zone.
And when updating thermal zone, we need to check the upper and lower limit
to make sure the cooling device is set to the proper cooling state.

Note that this patch will not bring any different behavior as
upper limit is set to max_state and lower limit is set to 0
in this patch, for now.

Next patch will set these to real values.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Rafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: Eduardo Valentin <eduardo.valentin@ti.com>