dccp: drop null test before destroy functions

Remove unneeded NULL test.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
expression x;
@@

-if (x != NULL)
  \(kmem_cache_destroy\|mempool_destroy\|dma_pool_destroy\)(x);

@@
expression x;
@@

-if (x != NULL) {
  \(kmem_cache_destroy\|mempool_destroy\|dma_pool_destroy\)(x);
  x = NULL;
-}
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dccp/ackvec.c

@@ -398,12 +398,8 @@ int __init dccp_ackvec_init(void)
 
 void dccp_ackvec_exit(void)
 {
-	if (dccp_ackvec_slab != NULL) {
 	kmem_cache_destroy(dccp_ackvec_slab);
 	dccp_ackvec_slab = NULL;
-	}
-	if (dccp_ackvec_record_slab != NULL) {
 	kmem_cache_destroy(dccp_ackvec_record_slab);
 	dccp_ackvec_record_slab = NULL;
-	}
 }

net/dccp/ccid.c

@@ -95,7 +95,6 @@ static struct kmem_cache *ccid_kmem_cache_create(int obj_size, char *slab_name_f
 
 static void ccid_kmem_cache_destroy(struct kmem_cache *slab)
 {
-	if (slab != NULL)
 	kmem_cache_destroy(slab);
 }