[VFS] Move victoria falls to rust. (Breaks voyageurs)

Move victoria falls to rust, which allows us to remove both the denali
and victoria falls C++ code. This disk driver appears to work properly
but has highlighted some instability in the voyageus xhci implementation
which now breaks.

rust/lib/mammoth/src/mem.rs

@@ -94,10 +94,21 @@ impl MemoryRegion {
         }
     }
 
+    pub fn raw_ptr_at_offset<T>(&self, offset: u64) -> *const T {
+        // TODO: Come up with a better safety check here.
+        // We can't use the size of T because it might not be sized.
+        assert!(offset + size_of::<T>() as u64 <= self.size);
+        (self.virt_addr + offset) as *const T
+    }
+
     pub fn cap(&self) -> &Capability {
         &self.mem_cap
     }
 
+    pub fn size(&self) -> u64 {
+        self.size
+    }
+
     pub fn duplicate(&self, offset: u64, length: u64) -> Result<Capability, ZError> {
         syscall::memory_obj_duplicate(&self.mem_cap, offset, length)
     }