Results 3 issues of LiWei

Hi , I have designed a zynq + ad9361 board which runs openwifi well .Hareware feature is : ZYNQ XC7Z020CLG400 ,1GB DDR3 memory fo PS, 1G ETHER RJ45 for PS,1G...

I added support of sdrpi for this branch , try pull request fro sdrpi hw,I will modify it if any error. I walked through all steps in readme.md and everything...

1.modifyb kernal_confid and dts to support dual ethernet 2,add description of sdrpi in README .