mpc52xx, digsy_mtc: change phy addr for rev5 boards.

- rev5 board has phy addr 1 -> adapt CONFIG_PHY_ADDR define
  in board config file.
- also fixup the phy addr entry in dts, before booting
  Linux.

Signed-off-by: Heiko Schocher <hs@denx.de>
Acked-by: Detlev Zundel <dzu@denx.de>