ARM: dts: socfpga: Drop phy-addr OF property from CV dtsi

The phy-addr property of stmmac is deprecated and the stmmac driver
does not use it either. On the contrary, the driver will warn if
this property is defined. Remove it.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Signed-off-by: Dinh Nguyen <dinguyen@opensource.altera.com>