drivers: net: davinci_mdio: remove pm runtime calls from suspend callbacks

PM runtime is disabled when Davinci MDIO .suspend_late() and
.resume_early() callbacks are called. As result, any PM runtime calls here will
be just a nop and can be removed.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>