crypto: img-hash - use dma_data_direction when calling dma_map_sg

The fourth argument of dma_map_sg() and dma_unmap_sg() is an item of
dma_data_direction enum. Function img_hash_xmit_dma() wrongly used
DMA_MEM_TO_DEV, which is an item of dma_transfer_direction enum.

Replace DMA_MEM_TO_DEV (which value is 1) with DMA_TO_DEVICE (which
value is fortunately also 1) when calling dma_map_sg() and
dma_unmap_sg().

Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>