PS0/PS3 methods to avoid lockups

[avilella]

Most look ups associated to suspend/hibernate or reboot into Windows can be avoided by using the _PS0 and _PS3 calls that many ACPI tables already have, instead of calling directly the _ON and _OFF methods. Calling the ON/OFF methods is the correct thing to do when switching the card on/off during a Linux session, for example in combination with the start/finish of the bumblebee deamon. But to make sure there are no side effects to it, the PS0/PS3 methods should hooked up into the user session so that they are appropriately called before suspending/hibernating/rebooting into Windows.