openvswitch: Use correct type while allocating flex array.

Flex array is used to allocate hash buckets which is type struct
hlist_head, but we use `struct hlist_head *` to calculate
array size.  Since hlist_head is of size pointer it works fine.

Following patch use correct type.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>

net/openvswitch/flow.c

@@ -240,7 +240,7 @@ static struct flex_array *alloc_buckets(unsigned int n_buckets)
 	struct flex_array *buckets;
 	int i, err;
 
-	buckets = flex_array_alloc(sizeof(struct hlist_head *),
+	buckets = flex_array_alloc(sizeof(struct hlist_head),
 				   n_buckets, GFP_KERNEL);
 	if (!buckets)
 		return NULL;