dt-bindings: panel: Add missing .txt suffix

All other files in that directory have a .txt suffix, so add one for
consistency.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20181203161310.15438-1-thierry.reding@gmail.com

diff --git a/Documentation/devicetree/bindings/display/panel/auo,g101evn010 b/Documentation/devicetree/bindings/display/panel/auo,g101evn010.txt
similarity index 100%
rename from Documentation/devicetree/bindings/display/panel/auo,g101evn010
rename to Documentation/devicetree/bindings/display/panel/auo,g101evn010.txt