target: Delete incorrect comment

aptpl_file_mutex seems to no longer exist.
Signed-off-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_pr.c

@@ -1927,9 +1927,6 @@ static int core_scsi3_update_aptpl_buf(
 	return ret;
 }
 
-/*
- * Called with struct se_device->aptpl_file_mutex held
- */
 static int __core_scsi3_write_aptpl_to_file(
 	struct se_device *dev,
 	unsigned char *buf)