The DMA API is preferred.

No functional change.
Signed-off-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: NLennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>