xfrm: remove unused struct xfrm_mgr::id

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/key/af_key.c

@@ -3792,7 +3792,6 @@ static inline void pfkey_exit_proc(struct net *net)
 
 static struct xfrm_mgr pfkeyv2_mgr =
 {
-	.id		= "pfkeyv2",
 	.notify		= pfkey_send_notify,
 	.acquire	= pfkey_send_acquire,
 	.compile_policy	= pfkey_compile_policy,