net: mv643xx_eth: Add missing phy_addr_set in DT mode

Commit cc9d4598

 'net: mv643xx_eth: use of_phy_connect if phy_node
present' made the call to phy_scan optional, if the DT has a link to
the phy node.

However phy_scan has the side effect of calling phy_addr_set, which
writes the phy MDIO address to the ethernet controller. If phy_addr_set
is not called, and the bootloader has not set the correct address then
the driver will fail to function.

Tested on Kirkwood.

Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Acked-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Tested-by: Arnaud Ebalard <arno@natisbad.org>
Signed-off-by: David S. Miller <davem@davemloft.net>