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

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>