dmaengine: Add an enum for the dmaengine alignment constraints

Most drivers need to set constraints on the buffer alignment for async tx
operations. However, even though it is documented, some drivers either use
a defined constant that is not matching what the alignment variable expects
(like DMA_BUSWIDTH_* constants) or fill the alignment in bytes instead of
power of two.

Add a new enum for these alignments that matches what the framework
expects, and convert the drivers to it.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index 88853af..3e5d4f1 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -1000,7 +1000,7 @@
 	 * code using dma memcpy must make sure alignment of
 	 * length is at dma->copy_align boundary.
 	 */
-	dma->copy_align = DMA_SLAVE_BUSWIDTH_4_BYTES;
+	dma->copy_align = DMAENGINE_ALIGN_4_BYTES;
 
 	INIT_LIST_HEAD(&dma->channels);
 }