arm64: dts: zynqmp: Fix leds subnode name for zcu100/ultra96 v1

Fix the leds subnode names to match (^led-[0-9a-f]$|led).

Similar change has been also done by commit 08dc0e5dd9 ("arm64: dts:
meson: fix leds subnodes name").

The patch is fixing this warning:
avnet-ultra96-rev1.dt.yaml: leds: 'ds2', 'ds3', 'ds4', 'ds5' do not match
any of the regexes: '(^led-[0-9a-f]$|led)', 'pinctrl-[0-9]+'

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/1a69c3fa0291f991ffcf113ea222c713ba4d4ff0.1598264917.git.michal.simek@xilinx.com

arch/arm64/boot/dts/xilinx/zynqmp-zcu100-revC.dts

@@ -56,27 +56,27 @@
 
 	leds {
 		compatible = "gpio-leds";
-		ds2 {
+		led-ds2 {
 			label = "ds2";
 			gpios = <&gpio 20 GPIO_ACTIVE_HIGH>;
 			linux,default-trigger = "heartbeat";
 		};
 
-		ds3 {
+		led-ds3 {
 			label = "ds3";
 			gpios = <&gpio 19 GPIO_ACTIVE_HIGH>;
 			linux,default-trigger = "phy0tx"; /* WLAN tx */
 			default-state = "off";
 		};
 
-		ds4 {
+		led-ds4 {
 			label = "ds4";
 			gpios = <&gpio 18 GPIO_ACTIVE_HIGH>;
 			linux,default-trigger = "phy0rx"; /* WLAN rx */
 			default-state = "off";
 		};
 
-		ds5 {
+		led-ds5 {
 			label = "ds5";
 			gpios = <&gpio 17 GPIO_ACTIVE_HIGH>;
 			linux,default-trigger = "bluetooth-power";