ipc/util: drop ipc_rcu_free()

There are no more callers of ipc_rcu_free(), so remove it.

Link: http://lkml.kernel.org/r/20170525185107.12869-9-manfred@colorfullife.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ipc/util.c

@@ -429,13 +429,6 @@ void ipc_rcu_putref(struct kern_ipc_perm *ptr,
 	call_rcu(&ptr->rcu, func);
 }
 
-void ipc_rcu_free(struct rcu_head *h)
-{
-	struct kern_ipc_perm *ptr = container_of(h, struct kern_ipc_perm, rcu);
-
-	kvfree(ptr);
-}
-
 /**
  * ipcperms - check ipc permissions
  * @ns: ipc namespace