modify some wrong func information in device_tool.go

Signed-off-by: lixiaobing10051267 <li.xiaobing1@zte.com.cn>

contrib/docker-device-tool/device_tool.go

@@ -161,7 +161,7 @@ func main() {
 
 		err := devices.MountDevice(args[1], args[2], "")
 		if err != nil {
-			fmt.Println("Can't create snap device: ", err)
+			fmt.Println("Can't mount device: ", err)
 			os.Exit(1)
 		}
 		break