dma: mv_xor: in mv_xor_chan, rename 'common' to 'dmachan'

The mv_xor_chan structure embeds a 'struct dma_chan', which is named
'common', a not very meaningful name. Rename it to 'dmachan', which
will help avoid confusions later as we merge the mv_xor_device and
mv_xor_chan structures together.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
diff --git a/drivers/dma/mv_xor.h b/drivers/dma/mv_xor.h
index 05add24..ad18f64 100644
--- a/drivers/dma/mv_xor.h
+++ b/drivers/dma/mv_xor.h
@@ -101,7 +101,7 @@
 	struct list_head	chain;
 	struct list_head	completed_slots;
 	struct mv_xor_device	*device;
-	struct dma_chan		common;
+	struct dma_chan		dmachan;
 	struct mv_xor_desc_slot	*last_used;
 	struct list_head	all_slots;
 	int			slots_allocated;