dt-bindings: Add a minimum version check for dtschema

The dtschema package must be somewhat up to date as the tools and
meta-schema checks are still evolving. Implement a version check,
so this can be enforced. This will help ensure new schema submissions
get checked against the latest meta-schemas.

Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>