This adds Nintendo Wii Balance Board support to the new HOTPLUG capable
wiimote core. It is mostly copied from the old extension.

This also adds Balance Board device detection. Whenever we find a device
that supports the balance-board extension, we assume that it is a real
balance board and disable unsupported hardward like accelerometer, IR,
rumble and more.
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>