HID: hid-lg4ff: Export the real wheel model and supported alternate modes

Display the real wheel model and supported alternate modes through sysfs. This
applies only to multimode wheels.

Signed-off-by: Michal Malý <madcatxster@devoid-pointer.net>
Tested-by: Simon Wood <simon@mungewell.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>