HID: wiimote: Parse calibration data of balance boards

The raw pressure-data that is reported by balance-boards is pretty useless
unless calibration data is applied. Therefore, we read the full
calibration data on extension initialization and apply it to every
reported data.

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