zynq7-base.dtsi: Add additional binding for OCM
zynq7-base.dtsi: Add additional binding for OCM

* Add the 3.10 compatiblity string for the OCM node

Signed-off-by: Nathan Rossi <e1e6d173c6873c0ae2b831215d22380d293bb314@xilinx.com>

Xilinx/meta-xilinx,Xilinx/meta-xilinx,nathanrossi/meta-xilinx,Xilinx/meta-xilinx,nathanrossi/meta-xilinx,nathanrossi/meta-xilinx,Xilinx/meta-xilinx,Xilinx/meta-xilinx,Xilinx/meta-xilinx,nathanrossi/meta-xilinx