Patch to revert parts of the tboot patches from Wed Feb 4 10:47:48.

Patch to revert parts of the tboot patches from Wed Feb 4 10:47:48.
This addresses the hang on the Lenovo laptops. More investigation
needs to be done as to why the hang occurs since the original changes
are not really incorrect. For not this will prevent the hang.

 Changes to be committed:
	modified:   xen/arch/x86/setup.c
	modified:   xen/arch/x86/tboot.c
	modified:   xen/drivers/passthrough/vtd/iommu.c