HID: wiimote: Add extension initializers

The wiimote extension registers are not fully understood, so we always disable
all extensions on extension-port events. Then we reinitialize and reidentify
them and activate all requested extensions.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>