lustre: remove unused declaration

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/drivers/staging/lustre/lustre/llite/llite_internal.h b/drivers/staging/lustre/lustre/llite/llite_internal.h
index ee8a1d6..845e992 100644
--- a/drivers/staging/lustre/lustre/llite/llite_internal.h
+++ b/drivers/staging/lustre/lustre/llite/llite_internal.h
@@ -631,8 +631,6 @@
 
 struct lov_stripe_md;
 
-extern spinlock_t inode_lock;
-
 extern struct dentry *llite_root;
 extern struct kset *llite_kset;