target: Remove obsolete DF_READ_ONLY usage

This was used at one time as a hack by FILEIO backend registration to
allow a struct block_device that was claimed with blkdev_get (by a local
filesystem mount for example) to be exported as read-only (SCSI WP=1).

Since FILEIO backend registration will no longer attempt to obtain
exclusive access to an underlying struct block_device here, this flag is
now obsolete.

Reported-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index aa62677..d175ee2 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -1341,7 +1341,6 @@
 	u32 lun)
 {
 	struct se_lun *lun_p;
-	u32 lun_access = 0;
 	int rc;
 
 	if (atomic_read(&dev->dev_access_obj.obj_access_count) != 0) {
@@ -1354,12 +1353,8 @@
 	if (IS_ERR(lun_p))
 		return lun_p;
 
-	if (dev->dev_flags & DF_READ_ONLY)
-		lun_access = TRANSPORT_LUNFLAGS_READ_ONLY;
-	else
-		lun_access = TRANSPORT_LUNFLAGS_READ_WRITE;
-
-	rc = core_tpg_post_addlun(tpg, lun_p, lun_access, dev);
+	rc = core_tpg_post_addlun(tpg, lun_p,
+				TRANSPORT_LUNFLAGS_READ_WRITE, dev);
 	if (rc < 0)
 		return ERR_PTR(rc);