target: kill struct se_subsystem_dev

Simplify the code a lot by killing the superflous struct se_subsystem_dev.
Instead se_device is allocated early on by the backend driver, which allocates
it as part of its own per-device structure, borrowing the scheme that is for
example used for inode allocation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/target/target_core_file.h b/drivers/target/target_core_file.h
index 876ae53..bc02b01 100644
--- a/drivers/target/target_core_file.h
+++ b/drivers/target/target_core_file.h
@@ -17,6 +17,8 @@
 #define FDBD_HAS_BUFFERED_IO_WCE 0x04
 
 struct fd_dev {
+	struct se_device dev;
+
 	u32		fbd_flags;
 	unsigned char	fd_dev_name[FD_MAX_DEV_NAME];
 	/* Unique Ramdisk Device ID in Ramdisk HBA */