dm: block: Rename device number member dev to devnum

This is a device number, and we want to use 'dev' to mean a driver model
device. Rename the member.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Stephen Warren <swarren@nvidia.com>
diff --git a/include/blk.h b/include/blk.h
index fd54520..9c54842 100644
--- a/include/blk.h
+++ b/include/blk.h
@@ -36,7 +36,7 @@
 
 struct blk_desc {
 	enum if_type	if_type;	/* type of the interface */
-	int		dev;		/* device number */
+	int		devnum;		/* device number */
 	unsigned char	part_type;	/* partition type */
 	unsigned char	target;		/* target SCSI ID */
 	unsigned char	lun;		/* target LUN */