devmapper: fix reloadPool() to also specify '1 skip_block_zeroing'

createPool() and reloadPool() should be consistent with the thin-pool
table params they use.

Since createPool() specifies '1 skip_block_zeroing' reloadPool() should
too.  Otherwise, if the pool is reloaded (as is done when resizing
loopback devices) block zeroing will be enabled after the reload
completes.

Docker-DCO-1.1-Signed-off-by: Mike Snitzer <snitzer@redhat.com> (github: snitm)

daemon/graphdriver/devmapper/devmapper.go

@@ -369,7 +369,7 @@ func reloadPool(poolName string, dataFile, metadataFile *os.File) error {
 		return fmt.Errorf("Can't get data size %s", err)
 	}
 
-	params := metadataFile.Name() + " " + dataFile.Name() + " 128 32768"
+	params := metadataFile.Name() + " " + dataFile.Name() + " 128 32768 1 skip_block_zeroing"
 	if err := task.AddTarget(0, size/512, "thin-pool", params); err != nil {
 		return fmt.Errorf("Can't add target %s", err)
 	}