ACPI: use handle, not device, in system notification path

This patch changes the global system notification path so it uses the
acpi_handle, not the acpi_device.

System notifications often deal with device presence and status change.
In these cases, we may not have an acpi_device.  For example, we may
get a Device Check notification on an object that previously was not
present.  Since the object was not present, we would not have had an
acpi_device for it.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>