Use dmaengine_prep_slave_sg inline function instead of going through the
structures manually.
Signed-off-by: Fabio Baltieri <fabio.baltieri@linaro.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>