[PKT_SCHED] ematch: Fix build warning.

Commit 954415e3 ("[PKT_SCHED] ematch:
tcf_em_destroy robustness") removed a cast on em->data when
passing it to kfree(), but em->data is an integer type that can
hold pointers as well as other values so the cast is necessary.
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/ematch.c

@@ -410,7 +410,7 @@ void tcf_em_tree_destroy(struct tcf_proto *tp, struct tcf_ematch_tree *tree)
 			if (em->ops->destroy)
 				em->ops->destroy(tp, em);
 			else if (!tcf_em_is_simple(em))
-				kfree(em->data);
+				kfree((void *) em->data);
 			module_put(em->ops->owner);
 		}
 	}