hidraw: document DJ report types
ltunify: ignore DJ reports

Fixes the warning messages below:

$ ltunify unpair 2
Unexpected disconnection type 0000
Device 0x02 Touchpad successfully unpaired
$ ltunify pair
Please turn your wireless device off and on to start pairing.
Found new device, id=0x02 Touchpad
Dev conn notif is expected to be short, got 0x20 instead
Dev conn notif is expected to be short, got 0x20 instead
Dev conn notif is expected to be short, got 0x20 instead
Dev conn notif is expected to be short, got 0x20 instead
Dev conn notif is expected to be short, got 0x20 instead
hidraw: do not interpret report ID for unknown report type
shell: support DJ reports