Fix IOMMU unassign bug and add translate opcode

unassign_device: clear DTE and submit hardware INVALIDATE_DEVTAB_ENTRY
and INVALIDATE_INTERRUPT_TABLE commands with completion wait (was
previously only clearing the software HashMap).

TRANSLATE opcode (0x0012): walk IOMMU page tables for IOVA-to-physical
address resolution.

fstat: return proper MODE_DIR/MODE_FILE and sizes for all handle kinds
(Root, Control, Domain, Device).

Remove #TODO from recipe.toml.

local/recipes/system/iommu/source/src/page_table.rs

@@ -628,6 +628,10 @@ impl DomainPageTables {
     pub fn mapping_count(&self) -> usize {
         self.mappings.len()
     }
+
+    pub fn translate(&self, iova: u64) -> Option<u64> {
+        self.page_table.translate(iova)
+    }
 }
 
 fn align_up(value: u64, align: u64) -> Option<u64> {