dt-bindings: Add vendor prefix for Chrontel, Inc.

Chrontel makes encoders for video displays and perhaps other stuff.
Their web site is http://www.chrontel.com/.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200424213539.93157-2-lkundrak@v3.sk