drivers: net: davinci_mdio: restore mdio clk divider in mdio resume

During suspend resume cycle all the register data is lost, so MDIO
clock divier value gets reset. This patch restores the clock divider
value.

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>