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/cmd/disk.c b/cmd/disk.c
index 0883c79..27ed115 100644
--- a/cmd/disk.c
+++ b/cmd/disk.c
@@ -45,7 +45,7 @@
 		return 1;
 	}
 
-	dev = dev_desc->dev;
+	dev = dev_desc->devnum;
 	bootstage_mark(BOOTSTAGE_ID_IDE_TYPE);
 
 	printf("\nLoading from %s device %d, partition %d: "