net: Add Freescale FMan ethernet support ...

This adds ethernet support for the Freecale Layerscape SoCs. The
architecture in these SoCs is called "Data Path Acceleration
Architecture" (DPAA). It is comprised of:

- The Queue Manager (QMan)
- Buffer Manager (BMan)
- Frame Manager (FMan)
- Multirate Ethernet Media Access Controller (mEMAC)

The code is based on the corresponding U-Boot driver enriched with
device tree parsing and proper device driver support.

Tested on LS1046a, should work on other SoCs aswell with some minor
quirks. SerDes support has been removed for now.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>