dt-bindings: qoriq-clock: add missing compatible for lx2160a

The compatible string is already in use, fix the binding to include it.
Signed-off-by: Li Yang <leoyang.li@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/clock/qoriq-clock.txt

@@ -44,6 +44,7 @@ Required properties:
 	* "fsl,ls1046a-clockgen"
 	* "fsl,ls1088a-clockgen"
 	* "fsl,ls2080a-clockgen"
+	* "fsl,lx2160a-clockgen"
 	Chassis-version clock strings include:
 	* "fsl,qoriq-clockgen-1.0": for chassis 1.0 clocks
 	* "fsl,qoriq-clockgen-2.0": for chassis 2.0 clocks