lightnvm: free properly on target creation error

Fix a memory leak when target creation fails. More specifically, free
the entire device structure given to the target (tgt_dev).

Signed-off-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <matias@cnexlabs.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/lightnvm/core.c

@@ -303,7 +303,7 @@ err_init:
 err_queue:
 	blk_cleanup_queue(tqueue);
 err_dev:
-	kfree(tgt_dev);
+	nvm_remove_tgt_dev(tgt_dev);
 err_t:
 	kfree(t);
 err_reserve: