ACPI: processor: Remove acpi_hwp_native_thermal_lvt_osc()

The workaround for buggy skylake BIOSes is now implemented in
acpi_processor_osc() and acpi_hwp_native_thermal_lvt_osc() has no
callers, so drop it.

Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Michal Wilczynski <michal.wilczynski@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>