arm64: dts: rockchip: Add support of regulator for ethernet node on Rock 3A SBC

Add regulator support for ethernet node

Fix following warning.
[    7.365199] rk_gmac-dwmac fe010000.ethernet: no regulator found

Signed-off-by: Anand Moon <linux.amoon@gmail.com>
Acked-by: Michael Riesch <michael.riesch@wolfvision.net>
Tested-by: Michael Riesch <michael.riesch@wolfvision.net>
Link: https://lore.kernel.org/r/20221116200150.4657-4-linux.amoon@gmail.com


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