Update call sites in the dma subsystem to import `ARef` and
`AlwaysRefCounted` from `sync::aref` instead of `types`.
This aligns with the ongoing effort to move `ARef` and
`AlwaysRefCounted` to sync.
Suggested-by: Benno Lossin <lossin@xxxxxxxxxx>
Link: https://github.com/Rust-for-Linux/linux/issues/1173
Signed-off-by: Shankari Anand <shankari.ak0208@xxxxxxxxx>