iommu-fixes-v4.20-rc3

Including:

	- Two fixes for the Intel VT-d driver to fix a NULL-ptr
	  dereference and an unbalance in an allocate/free path
	  (allocated with memremap, freed with iounmap)

	- Fix for a crash in the Renesas IOMMU driver

	- Fix for the Advanced Virtual Interrupt Controler (AVIC) code
	  in the AMD IOMMU driver