sun7i-nand: add initial sun7i-nand support
It seems work with github.com/cubieboard2/linux-sunxi hans-sunxi-3.4 branch. I merge the nand driver source provided by kevin@allwinnertech.com from 3.3, and make it built-in
with 2 separate modules.
1. sun7i-nandlib
2. sun7i-nand
I am not export of nand, so please more refactoring is needed

Signed-off-by: benn <benn@cubietech.com>
cubieboard2: to enable sun7i-nandlib, sun7i-nand

Signed-off-by: benn <benn@cubietech.com>