arm64: dts: rockchip: fix adc-keys sub node names

Fix adc-keys sub node names on Rockchip boards,
so that they match with regex: '^button-'

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Link: https://lore.kernel.org/r/6a6a3603-5540-cacc-2672-c015af1ec684@gmail.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>