Once the MDIO state machine has been initialized and enabled, it
starts polling all 32 PHY addresses on the MDIO bus, looking for
an active PHY. Add a 5 ms delay, so all PHYs are for sure detected.

This problem was detected on the cmc board with a KSZ8864 switch.

Signed-off-by: Heiko Schocher <hs@denx.de>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>