crypto: ux500/hash - Set DMA configuration though dma_slave_config()

The DMA controller currently takes configuration information from
information passed though dma_channel_request(), but it shouldn't.
Using the API, the DMA channel should only be configured during
a dma_slave_config() call.

Cc: David S. Miller <davem@davemloft.net>
Cc: Andreas Westin <andreas.westin@stericsson.com>
Cc: linux-crypto@vger.kernel.org
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>