of: Add vendor prefix for Shanghai AVIC Optoelectronics Co., Ltd.

Shanghai AVIC Optoelectronics Co., Ltd. is a subsidiary of Tianma
Microelectronics Co., Ltd. and designs and manufactures TFT LCDs.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>