ipv6: Remove superfluous NULL pointer check in ipv6_local_rxpmtu

The pointer to mtu_info is taken from the common buffer
of the skb, thus it can't be a NULL pointer. This patch
removes this check on mtu_info.
Signed-off-by: NSteffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/datagram.c

@@ -297,10 +297,6 @@ void ipv6_local_rxpmtu(struct sock *sk, struct flowi6 *fl6, u32 mtu)
 	ipv6_addr_copy(&iph->daddr, &fl6->daddr);
 
 	mtu_info = IP6CBMTU(skb);
-	if (!mtu_info) {
-		kfree_skb(skb);
-		return;
-	}
 
 	mtu_info->ip6m_mtu = mtu;
 	mtu_info->ip6m_addr.sin6_family = AF_INET6;