Fix shutdown/reboot bug for u8500 devices

This should fix issues reported here:
http://forum.xda-developers.com/showpost.php?p=51314505&postcount=121
http://forum.xda-developers.com/showpost.php?p=51314582&postcount=122

Change-Id: Ida3089569058abb96a097a1041cbe61747c8d63a