Add additional property info needed for DSIv2 DT.

Cc: devicetree@vger.kernel.org
Cc: Rob Herring <robh@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>