arm64: dts: k3-am654-base-board: add mcu cpsw nuss pinmux and phy defs

AM654 EVM base board has TI DP83867 PHY connected to external CPSW NUSS
Port 1 in rgmii-rxid mode.

Hence, add pinmux and Ethernet PHY configuration for TI am654 SoC Gigabit
Ethernet two ports Switch subsystem (CPSW NUSS).

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Tested-by: Murali Karicheri <m-karicheri2@ti.com>
Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>