arm64: dts: rockchip: Clean up gpio-keys nodes

Drop superfluous #address-cells and #size-cells.
Use KEY_POWER define for 116.
Rename sub-nodes to avoid new dtc warnings.

Reported-by: Julien Chauveau <chauveau.julien@gmail.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Reviewed-by: Julien Chauveau <chauveau.julien@gmail.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>