af_key: Fix af_key.c compiler warning

net/key/af_key.c: In function ‘pfkey_spddelete’:
net/key/af_key.c:2359: warning: ‘pol_ctx’ may be used uninitialized in 
this function

When CONFIG_SECURITY_NETWORK_XFRM isn't set, 
security_xfrm_policy_alloc() is an inline that doesn't set pol_ctx, so 
this seemed like the easiest fix short of using *uninitialized_var(pol_ctx).
Signed-off-by: NBrian Haley <brian.haley@hp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/key/af_key.c

@@ -2356,7 +2356,7 @@ static int pfkey_spddelete(struct sock *sk, struct sk_buff *skb, struct sadb_msg
 	struct xfrm_selector sel;
 	struct km_event c;
 	struct sadb_x_sec_ctx *sec_ctx;
-	struct xfrm_sec_ctx *pol_ctx;
+	struct xfrm_sec_ctx *pol_ctx = NULL;
 
 	if (!present_and_same_family(ext_hdrs[SADB_EXT_ADDRESS_SRC-1],
 				     ext_hdrs[SADB_EXT_ADDRESS_DST-1]) ||
@@ -2396,8 +2396,7 @@ static int pfkey_spddelete(struct sock *sk, struct sk_buff *skb, struct sadb_msg
 		kfree(uctx);
 		if (err)
 			return err;
-	} else
-		pol_ctx = NULL;
+	}
 
 	xp = xfrm_policy_bysel_ctx(XFRM_POLICY_TYPE_MAIN,
 				   pol->sadb_x_policy_dir - 1, &sel, pol_ctx,