Freezer: Fix s2disk resume from initrd

Add appropriate freezer annotations to handle_initrd(), so that it's possible
to resume from disk from an initrd.

http://bugzilla.kernel.org/show_bug.cgi?id=9345

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Chris Friedhoff <chris@friedhoff.org>
Signed-off-by: Len Brown <len.brown@intel.com>