ARM: zynq: Fix leds subnode name for zc702/zybo-z7

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

Similar change has been also done by commit 9a19a39ee48b ("arm64: dts:
zynqmp: Fix leds subnode name for zcu100/ultra96 v1").

The patch is fixing these warnings:
.../zynq-zc702.dt.yaml: leds: 'ds23' does not match any of the regexes:
'(^led-[0-9a-f]$|led)', 'pinctrl-[0-9]+'
>From schema: .../Documentation/devicetree/bindings/leds/leds-gpio.yaml
.../zynq-zybo-z7.dt.yaml: gpio-leds: 'ld4' does not match any of the
regexes: '(^led-[0-9a-f]$|led)', 'pinctrl-[0-9]+'
>From schema: .../Documentation/devicetree/bindings/leds/leds-gpio.yaml

Signed-off-by: Michal Simek <[e-mail]>
Link: https://lore.kernel.org/r/607a[e-mail]

arch/arm/boot/dts/zynq-zc702.dts

···
 	leds {
 		compatible = "gpio-leds";
 
-		ds23 {
+		led-ds23 {
 			label = "ds23";
 			gpios = <&gpio0 10 0>;
 			linux,default-trigger = "heartbeat";

arch/arm/boot/dts/zynq-zybo-z7.dts

···
 	gpio-leds {
 		compatible = "gpio-leds";
 
-		ld4 {
+		led-ld4 {
 			label = "zynq-zybo-z7:green:ld4";
 			gpios = <&gpio0 7 GPIO_ACTIVE_HIGH>;
 		};