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/disk/part_efi.c b/disk/part_efi.c
index 209a671..ae8cd7e 100644
--- a/disk/part_efi.c
+++ b/disk/part_efi.c
@@ -356,7 +356,7 @@
 	/* Write MBR sector to the MMC device */
 	if (dev_desc->block_write(dev_desc, 0, 1, p_mbr) != 1) {
 		printf("** Can't write to device %d **\n",
-			dev_desc->dev);
+			dev_desc->devnum);
 		return -1;
 	}
 
@@ -410,7 +410,7 @@
 	return 0;
 
  err:
-	printf("** Can't write to device %d **\n", dev_desc->dev);
+	printf("** Can't write to device %d **\n", dev_desc->devnum);
 	return -1;
 }