This patch adds a .notify() method.  The presence of .notify() causes
Linux/ACPI to manage event handlers and notify handlers on our behalf,
so we don't have to install and remove them ourselves.
Signed-off-by: NBjorn Helgaas <bjorn.helgaas@hp.com>
CC: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: NLen Brown <len.brown@intel.com>