Document the AST2600 I2C bus compatible string.
Signed-off-by: NEddie James <eajames@linux.ibm.com>
Reviewed-by: NBrendan Higgins <brendanhiggins@google.com>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>