Fix the same incorrect assumption in replace_vma
Fix the same incorrect assumption in replace_vma

Here we already treat the radix tree as the source of truth, so we
don't actually care if the VMA has been deleted or not.

aclements/sv6,bowlofstew/sv6,aclements/sv6,bowlofstew/sv6,bowlofstew/sv6,aclements/sv6,bowlofstew/sv6,aclements/sv6,aclements/sv6,bowlofstew/sv6