crypto: ux500: use dmaengine_submit API

Use dmaengine_submit instead of calling desc->tx_submit 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>