Since we no longer allocate the iommu page tables in pmap_bootstrap, we can remove unavail_{start,end} and simplify the code in pmap_page_upload.
Since we no longer allocate the iommu page tables in pmap_bootstrap, we can
remove unavail_{start,end} and simplify the code in pmap_page_upload.

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars