dt-bindings: i2c: Convert arm,i2c-versatile to DT schema

Convert the arm,i2c-versatile binding to DT schema format.

Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
[wsa: fixed "arn" typo spotted by Krzysztof]
Signed-off-by: Wolfram Sang <wsa@kernel.org>