HID: wiimote: Add wiimote input button parser

Parse input report 0x30 from the wiimote as button input. We need to
send events for all buttons on every input report because the wiimote
does not send events for single buttons but always for all buttons
to us. The input layer, however, filters redundant events.

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