powerpc/44x: Use correct phy-address dt nodes on taishan.dts

Taishan (440GX) has the first PHY (EMAC2) mapped at PHY address 1
and the 2nd PHY (EMAC3) at PHY address 3. Use "phy-address" to
correctly describe this instead of "phy-map".

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>