sh_eth: Use platform device for printing before register_netdev()

[ Upstream commit 5f5c5449acad0cd3322e53e1ac68c044483b0aa5 ]

The MDIO initialization failure message is printed using the network
device, before it has been registered, leading to:

     (null): failed to initialise MDIO

Use the platform device instead to fix this:

    sh-eth ee700000.ethernet: failed to initialise MDIO

Fixes: daacf03f ("sh_eth: Register MDIO bus before registering the network device")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>