Split-out struct iommu_unit, iommu_domain and iommu_ctx to a separate file iommu_var.h, so we can include 'dev/iommu/iommu.h' without dependencies like pci_var.h, pci_reg.h etcThis allows the interrupt controller driver only need a small change to create a map for the page the device will write to raise an interrupt.
This will be needed for subr_intr.co Split-out GAS macroses to a separate header iommu_gas.h
o Add iommu_msi.h