DT: Vendor prefixes: Add ricoh, qnap, sii and synology

The following patches make use of vendor names:
* ricoh (Ricoh Co. Ltd.);
* qnap (QNAP Systems, Inc.);
* sii (Seiko Instruments, Inc.); and
* synology (Synology, Inc.)

Add them to the vendor prefix list.

Signed-off-by: Ben Peddell <klightspeed@killerwolves.net>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Jason Cooper <jason@lakedaemon.net>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>