arm64: dts: ti: k3-j721e-common-proc-board: add mcu cpsw nuss pinmux and phy defs

The TI J721E 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 j721e SoC MCU
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>