riscv: dts: starfive: visionfive 2: Add configuration of gmac and phy

riscv: dts: starfive: visionfive 2: Add configuration of gmac and phy

v1.3B:
  v1.3B uses motorcomm YT8531(rgmii-id phy) x2, need delay and
  inverse configurations.
  The tx_clk of v1.3B uses an external clock and needs to be
  switched to an external clock source.

v1.2A:
  v1.2A gmac0 uses motorcomm YT8531(rgmii-id) PHY, and needs delay
  configurations.
  v1.2A gmac1 uses motorcomm YT8512(rmii) PHY, and needs to
  switch rx and rx to external clock sources.

Tested-by: Tommaso Merciai <tomm.merciai@gmail.com>
Signed-off-by: Samin Guo <samin.guo@starfivetech.com>
[conor: squashed a fix from Samin to use the actual properties]
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>