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