target: mark tcm_loop_primary static

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/loopback/tcm_loop.c

@@ -108,7 +108,7 @@ static struct device_driver tcm_loop_driverfs = {
 /*
  * Used with root_device_register() in tcm_loop_alloc_core_bus() below
  */
-struct device *tcm_loop_primary;
+static struct device *tcm_loop_primary;
 
 static void tcm_loop_submission_work(struct work_struct *work)
 {