HID: logitech-hidpp: notify battery on connect

When a device reconnects, there is a high chance its power supply has
been changed (for a battery replacement for instance). Just forward
the battery state here.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Tested-by: Bastien Nocera <hadess@hadess.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>