ACPI: thermal: Eliminate code duplication from acpi_thermal_notify()

Move the acpi_bus_generate_netlink_event() invocation into
acpi_thermal_trips_update() which allows the code duplication in
acpi_thermal_notify() to be cleaned up, but for this purpose the
event value needs to be passed to acpi_thermal_trips_update() and
from there to acpi_thermal_adjust_thermal_zone() which has to
determine the flag value for __acpi_thermal_trips_update() by
itself.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>