xfrm: get rid of another incorrect WARN

During fuzzing I regularly run into this WARN(). According to Herbert Xu,
this "certainly shouldn't be a WARN, it probably shouldn't print anything
either".

Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NVegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: NSteffen Klassert <steffen.klassert@secunet.com>

net/xfrm/xfrm_user.c

@@ -2051,9 +2051,6 @@ static int xfrm_add_pol_expire(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (up->hard) {
 		xfrm_policy_delete(xp, p->dir);
 		xfrm_audit_policy_delete(xp, 1, true);
-	} else {
-		// reset the timers here?
-		WARN(1, "Don't know what to do with soft policy expire\n");
 	}
 	km_policy_expired(xp, p->dir, up->hard, nlh->nlmsg_pid);