crypto: atmel-{aes,sha,tdes} - Drop duplicate init of dma_slave_config.direction

The 'direction' member of the dma_slave_config will be going away
as it duplicates the direction given in the prepare call.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>