NET: au1000-eth: Convert to platform_driver model

This patch converts the au1000-eth driver to become a full platform-driver
as it ought to be. We now pass PHY-speficic configurations through
platform_data but for compatibility the driver still assumes the default
settings (search for PHY1 on MAC0) when no platform_data is passed. Tested
on my MTX-1 board.

Signed-off-by: Florian Fainelli <florian@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: netdev@vger.kernel.org
Acked-by: David S. Miller <davem@davemloft.net>
Patchwork: http://patchwork.linux-mips.org/patch/619/
Patchwork: http://patchwork.linux-mips.org/patch/963/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>