netfilter: conntrack: __nf_ct_l4proto_find() always returns valid pointer

Remove unnecessary check for non-nul pointer in destroy_conntrack()
given that __nf_ct_l4proto_find() returns the generic protocol tracker
if the protocol is not supported.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_conntrack_core.c

@@ -363,7 +363,7 @@ destroy_conntrack(struct nf_conntrack *nfct)
 	}
 	rcu_read_lock();
 	l4proto = __nf_ct_l4proto_find(nf_ct_l3num(ct), nf_ct_protonum(ct));
-	if (l4proto && l4proto->destroy)
+	if (l4proto->destroy)
 		l4proto->destroy(ct);
 
 	rcu_read_unlock();