HID: wiimote: remove old static extension support

We now have dynamic hotplug support so the old static extensions are no
longer needed nor used. Remove it along CONFIG_HID_WIIMOTE_EXT.

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