crypto: mxs-dcp - fix source scatterlist length access

crypto: mxs-dcp - fix source scatterlist length access

mxs_dcp_aes_block_crypt() uses sg_dma_len() without mapping the source
scatterlist with dma_map_sg() first. Therefore, sg_dma_len() is invalid
and could return zero or a stale DMA length, causing encryption and
decryption to process the wrong number of bytes when
CONFIG_NEED_SG_DMA_LENGTH=y.

Use the original scatterlist length instead.

Fixes: 15b59e7c3733 ("crypto: mxs - Add Freescale MXS DCP driver")
Cc: stable@vger.kernel.org
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>