dt-bindings: display: bridge: lvds-codec: Fix duplicate key

In order to validate multiple "if" conditionals, they must be part of an
"allOf:" list, otherwise they will cause a failure in parsing the schema
because of the duplicated "if" property.

Fixes: d7df3948 ("dt-bindings: display: bridge: lvds-codec: Document pixel data sampling edge select")
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20211220125147.519880-1-thierry.reding@gmail.com