xen-blkfront: fix data size for xenbus_gather in blkfront_connect

barrier variable is int, not long. This overflow caused another variable
override: "err" (in PV code) and "binfo" (in xenlinux code -
drivers/xen/blkfront/blkfront.c). The later caused incorrect device
flags (RO/removable etc).
Signed-off-by: Marek Marczykowski <marmarek@mimuw.edu.pl>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
[v1: Changed title]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/block/xen-blkfront.c

@@ -1141,7 +1141,7 @@ static void blkfront_connect(struct blkfront_info *info)
 	}
 
 	err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
-			    "feature-barrier", "%lu", &barrier,
+			    "feature-barrier", "%d", &barrier,
 			    NULL);
 
 	/*