ACPI: battery drivers should call power_supply_changed()

Calling kobject_uevent() directly is a layering violation.  In
particular, it means we'll miss updating the generic LED trigger.

Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Acked-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>