of: Add vendor prefix for Tianma Micro-electronics

Tianma Micro-electronics Co., Ltd. (Tianma) specializes in providing
display solutions and efficient support services worldwide.

More info:
http://en.tianma.com/about.shtml



Signed-off-by: Gary Bisson <gary.bisson@boundarydevices.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>