HID: hid-logitech-hidpp: Add basic support for Logitech G920

This patch adds basic support for the Logitech G920 wheel when in HID
mode. This wheel 'speaks' the HID++ protocol, and therefor is driven
with hid-logitech-hidpp.

At this stage the driver only shows that it can communicate with the
wheel by outputting the name discovered over HID++.

The normal HID functions work to give input functionality using
joystick/event interface.

Note: in 'hidpp_probe()' we have to start the hardware to get packets
flowing, the same might apply in future for other devices which don't
use the unifying protocol.

Signed-off-by: Simon Wood <simon@mungewell.org>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>