dmaengine, async_tx: support alignment checks

Some engines have transfer size and address alignment restrictions.  Add
a per-operation alignment property to struct dma_device that the async
routines and dmatest can use to check alignment capabilities.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/crypto/async_tx/async_memcpy.c b/crypto/async_tx/async_memcpy.c
index b38cbb3..0ec1fb6 100644
--- a/crypto/async_tx/async_memcpy.c
+++ b/crypto/async_tx/async_memcpy.c
@@ -50,7 +50,7 @@
 	struct dma_device *device = chan ? chan->device : NULL;
 	struct dma_async_tx_descriptor *tx = NULL;
 
-	if (device) {
+	if (device && is_dma_copy_aligned(device, src_offset, dest_offset, len)) {
 		dma_addr_t dma_dest, dma_src;
 		unsigned long dma_prep_flags = 0;