iommu-fixes-v3.6-rc1

These patches fix a couple of issues. First of all a few problems with
ACS on x86 introduced in the last merge window, where ACS did not work
on AMD and a NULL pointer dereference when there ran against SR-IOV
devices.
The patches fallen out of coccinelle checks fix a possible invalid
memory reference and a possible memory leak. The other patches mostly
fix build errors and warnings and a wrong return value.