dt-bindings: crypto: convert Inside Secure SafeXcel to the json-schema

This helps validating DTS files.

Cc: Antoine Tenart <atenart@kernel.org>
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>