dt-bindings: vendor-prefixes: correct the spelling of TQ-Systems GmbH

"TQ-Systems" is written with a dash, as can be seen on
https://www.tq-group.com/en/imprint/



Signed-off-by: Max Merchel <Max.Merchel@tq-group.com>
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Link: https://lore.kernel.org/r/20201207093036.29824-1-matthias.schiffer@ew.tq-group.com


Signed-off-by: Rob Herring <robh@kernel.org>