[RFC][TRUSTY] X-Gene platform support

[Dann Frazier]

fyi, I've updated my trusty-xgene staging trees:
  git://kernel.ubuntu.com/dannf/trusty-xgene.git for-ubuntu-20140317
  git://kernel.ubuntu.com/dannf/trusty-xgene.git for-ubuntu-20140317-oldpci

Changes:
 - Rebased on Ubuntu 3.13.0-18.38
 - xgene-ahci was accepted into the libata/next branch, merged this version
 - Updated pci changes from latest upstream submittal (-oldpci is the same)