ACPI: thermal: Mark uninitialized active trips as invalid

After removing the valid flag from struct acpi_thermal_trip, the trip
temperature value is used in validity checks, so it must be
THERMAL_TEMP_INVALID for the active trip entries in struct acpi_thermal_trips
that are not going to be used (because the corresponding objects are not
present in the ACPI tables, for example).

Accordingly, modify acpi_thermal_get_trip_points() to set the temperature
value to THERMAL_TEMP_INVALID for trip point entries skipped by it after
acpi_thermal_init_trip() has returned 'false' for an active trip.

Fixes: 058f5e40 ("ACPI: thermal: Drop valid flag from struct acpi_thermal_trip")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>