arm64: zynqmp: Setup clock-output-names for si570 chips

If there are more instances of si570 clock-output-names property
should be used for differentiation of clock output.
The patch is adding this optional properties for all zynqmp boards with
si570 chip.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/arch/arm/dts/zynqmp-zcu111-revA.dts b/arch/arm/dts/zynqmp-zcu111-revA.dts
index 346e631..172e6cc 100644
--- a/arch/arm/dts/zynqmp-zcu111-revA.dts
+++ b/arch/arm/dts/zynqmp-zcu111-revA.dts
@@ -318,6 +318,7 @@
 				temperature-stability = <50>;
 				factory-fout = <300000000>;
 				clock-frequency = <300000000>;
+				clock-output-names = "si570_user";
 			};
 		};
 		i2c@3 {
@@ -331,6 +332,7 @@
 				temperature-stability = <50>;
 				factory-fout = <156250000>;
 				clock-frequency = <148500000>;
+				clock-output-names = "si570_mgt";
 			};
 		};
 		i2c@4 {