ACPI: battery: Call power_supply_changed() when adding hooks

If a battery hook is added to a battery, userspace software
is not informed that the available properties of the battery
might have changed. This for example causes upower to react
slowly if a new battery hook is added during runtime.

Fix this by calling power_supply_changed() if a battery hook
was successfully added/removed.

Tested on a Dell Inspiron 3505.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>