dt-bindings: arm: xilinx: Add missing Zturn boards

Add missing DT compatible strings for Zturn boards.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/f6f642d75c1b1160ed78f6de0a2944ab64017691.1612185370.git.michal.simek@xilinx.com


Acked-by: Rob Herring <robh@kernel.org>