dcb_doit: remove redundant skb check

skb cannot be NULL here since its already being accessed
before: sock_net(skb->sk). Remove the redundant null check.
Signed-off-by: NGaurav Singh <gaurav1086@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/dcb/dcbnl.c

@@ -1736,7 +1736,7 @@ static int dcb_doit(struct sk_buff *skb, struct nlmsghdr *nlh,
 	struct net_device *netdev;
 	struct dcbmsg *dcb = nlmsg_data(nlh);
 	struct nlattr *tb[DCB_ATTR_MAX + 1];
-	u32 portid = skb ? NETLINK_CB(skb).portid : 0;
+	u32 portid = NETLINK_CB(skb).portid;
 	int ret = -EINVAL;
 	struct sk_buff *reply_skb;
 	struct nlmsghdr *reply_nlh = NULL;