MIPS: Lantiq: Add ethernet driver

This patch adds the driver for the ETOP Packet Processing Engine (PPE32)
found inside the XWAY family of Lantiq MIPS SoCs. This driver makes 100MBit
ethernet work. Support for all 8 dma channels, gbit and the embedded switch
found on the ar9/vr9 still needs to be implemented.

Signed-off-by: John Crispin <blogic@openwrt.org>
Signed-off-by: Ralph Hempel <ralph.hempel@lantiq.com>
Cc: linux-mips@linux-mips.org
Cc: netdev@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/2357/
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>