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/common/fb_mmc.c b/common/fb_mmc.c
index d5c9135..da7949f 100644
--- a/common/fb_mmc.c
+++ b/common/fb_mmc.c
@@ -86,7 +86,7 @@
 
 	blks = dev_desc->block_write(dev_desc, info->start, blkcnt, buffer);
 	if (blks != blkcnt) {
-		error("failed writing to device %d\n", dev_desc->dev);
+		error("failed writing to device %d\n", dev_desc->devnum);
 		fastboot_fail(response_str, "failed writing to device");
 		return;
 	}
@@ -207,7 +207,7 @@
 
 	blks = dev_desc->block_erase(dev_desc, blks_start, blks_size);
 	if (blks != blks_size) {
-		error("failed erasing from device %d", dev_desc->dev);
+		error("failed erasing from device %d", dev_desc->devnum);
 		fastboot_fail(response_str, "failed erasing from device");
 		return;
 	}