thermal/debugfs: Clean up thermal_debug_update_temp()

thermal/debugfs: Clean up thermal_debug_update_temp()

Notice that it is not necessary to compute tze in every iteration of the
for () loop in thermal_debug_update_temp() because it is the same for all
trips, so compute it once before the loop starts.

Also use a trip_stats local variable to make the code in that loop easier
to follow and move the trip_id variable definition into that loop because
it is not used elsewhere in the function.

While at it, change to order of local variable definitions in the function
to follow the reverse-xmas-tree pattern.

No intentional functional impact.

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