PM / Freezer: Fix small typo "regrigerator"

Noticed when digging into a suspend issue in linux-next (next-20120821).

For more details see <http://marc.info/?t=134554708000002&r=1&w=2

>.

Signed-off-by: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>