x86, mce: therm_throt - change when we print messages

My Latitude d630 seems to be handling thermal events in SMI by
lowering the max frequency of the CPU till it cools down but
still leaks the "everything is normal" events.

This spams the console and with high priority printks.

Adjust therm_throt driver to only print messages about the fact
that temperatire returned back to normal when leaving the
throttling state.

Also lower the severity of "back to normal" message from
KERN_CRIT to KERN_INFO.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Acked-by: H. Peter Anvin <hpa@zytor.com>
LKML-Reference: <20090810051513.0558F526EC9@mailhub.coreip.homeip.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>