target: Use a PASSTHROUGH flag instead of transport_types

It seems like we only care if a transport is passthrough or not. Convert
transport_type to a flags field and replace TRANSPORT_PLUGIN_* with a
flag, TRANSPORT_FLAG_PASSTHROUGH.

Signed-off-by: Andy Grover <agrover@redhat.com>
Reviewed-by: Ilias Tsitsimpis <iliastsi@arrikto.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/include/target/target_core_backend.h b/include/target/target_core_backend.h
index 563e119..5f12257 100644
--- a/include/target/target_core_backend.h
+++ b/include/target/target_core_backend.h
@@ -1,9 +1,7 @@
 #ifndef TARGET_CORE_BACKEND_H
 #define TARGET_CORE_BACKEND_H
 
-#define TRANSPORT_PLUGIN_PHBA_PDEV		1
-#define TRANSPORT_PLUGIN_VHBA_PDEV		2
-#define TRANSPORT_PLUGIN_VHBA_VDEV		3
+#define TRANSPORT_FLAG_PASSTHROUGH		1
 
 struct target_backend_cits {
 	struct config_item_type tb_dev_cit;
@@ -22,7 +20,7 @@
 	char inquiry_rev[4];
 	struct module *owner;
 
-	u8 transport_type;
+	u8 transport_flags;
 
 	int (*attach_hba)(struct se_hba *, u32);
 	void (*detach_hba)(struct se_hba *);