dt-bindings: panel: Document some missing compatible strings

Add missing compatible strings for the Panasonic and Chunghwa panels
found on NVIDIA Dalmore and Cardhu boards.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200417065328.1578603-1-thierry.reding@gmail.com