ARM64: dts: rockchip: Add gmac2phy node support for rk3328

The gmac2phy controller of rk3328 is connected to integrated PHY
directly inside, add the node for the integrated PHY support.

Signed-off-by: David Wu <david.wu@rock-chips.com>
Signed-off-by: David S. Miller <davem@davemloft.net>