x86, mce: unify smp_thermal_interrupt

Put common functions into therm_throt.c, modify Makefile.

	unexpected_thermal_interrupt
	intel_thermal_interrupt
	smp_thermal_interrupt
	intel_set_thermal_handler

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>