ath79, brcm63xx: Fix debounce-interval properties in gpio-keys-polled nodes

This patch fixes wrong usage of debounce-interval subnode property of
gpio-keys-polled nodes, which was used inproperly in parent node, but it
belongs to the subnodes, excerpt from the docs:

 Optional subnode-properties:
     - debounce-interval: Debouncing interval time in milliseconds.
       If not specified defaults to 5.

And the docs are up to date as the source code matches that description
as well:

 if (fwnode_property_read_u32(child, "debounce-interval",
                              &button->debounce_interval))
         button->debounce_interval = 5;

While at it, I've also re-formatted gpio-keys-polled nodes, usually just
adding new lines after every key subnode.

Cc: Tomasz Maciej Nowak <tomek_n@o2.pl>
Cc: Matt Merhar <mattmerhar@protonmail.com>
Cc: Jonas Gorski <jonas.gorski@gmail.com>
Signed-off-by: Petr Štetiar <ynezz@true.cz>

target/linux/ath79/dts/ar7161_ubnt_routerstation.dtsi

@@ -38,12 +38,12 @@
 	gpio-keys-polled {
 		compatible = "gpio-keys-polled";
 		poll-interval = <20>;
-		debounce-interval = <60>;
 
 		wps {
 			label = "sw4";
 			linux,code = <KEY_RESTART>;
 			gpios = <&gpio 8 GPIO_ACTIVE_LOW>;
+			debounce-interval = <60>;
 		};
 	};
 };