net: mvpp2: remove redundant SMI address configuration

Because the mvpp2 driver now relies on the PHYLIB and
the external MDIO driver, configuring low level
SMI bus settings is redundant.

Signed-off-by: Marcin Wojtas <mw@semihalf.com>
Reviewed-by: Kostya Porotchkin <kostap@marvell.com>
Reviewed-by: Stefan Chulski <stefanc@marvell.com>
Signed-off-by: Stefan Roese <sr@denx.de>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>