net: phy: Initialize mdio clock at probe function

commit bb1a619735b4660f21bce3e728b937640024b4ad upstream.

USB PHYs need the MDIO clock divisor enabled earlier to work.
Initialize mdio clock divisor in probe function. The ext bus
bit available in the same register will be used by mdio mux
to enable external mdio.

Signed-off-by: Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>
Fixes: ddc24ae1 ("net: phy: Broadcom iProc MDIO bus driver")
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jon Mason <jon.mason@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>