arm64: dts: lx2160a: add RGMII phy nodes

Annotate the EMDIO1 node and describe the 2 AR8035 RGMII PHYs.
Also, add phy-handles for dpmac17 and dpmac18 to its associated PHY.
The MAC is not capable to add the needed RGMII delays, thus the
"rgmii-id" phy-connection-type is used.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>