net:sunxi-gmac: add gmac support

The commit itself comes from

https://github.com/cubieboard/linux-sunxi/tree/cubie/sunxi-3.4/

IRC user jemk found out the IP itself comes from DesignWare. It turns
out it is supported already in both the mainline (stmmac) and the
U-Boot (designware). These existing drivers should be made to work
with Allwinner chips. This driver is solely for the purpose of the
reference and will not be improved.

Signed-off-by: arokux <arokux@gmail.com>
sunxi: script: remove incorrect Allwinner copyright

Signed-off-by: Alejandro Mery <amery@geeks.cl>
arm:sunxi:devices: scan script.bin detecting sections that define features
arm:sunxi:devices: check if features are to be enabled or not
arm:sunxi:devices: introduce pdev constructor

Signed-off-by: Alejandro Mery <amery@geeks.cl>