arm64: dts: rockchip: Update nanopi4 phy reset properties

Use the now-preferred generic phy reset properties instead of the
dwmac-specific ones.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/4d16c24ae3651a2119cf5bb1213f46a9fce4b39a.1570444773.git.robin.murphy@arm.com


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