powerpc/config: Enable MDIO support

Also, enable Vitesse PHY and fixed PHY support.

Signed-off-by: Andy Fleming <afleming@gmail.com>
Signed-off-by: Shaohui Xie <Shaohui.Xie@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>

diff --cc arch/powerpc/configs/corenet32_smp_defconfig
Simple merge

diff --cc arch/powerpc/configs/corenet64_smp_defconfig
Simple merge