macvtap: correctly free skb during socket destruction

We should use kfree_skb() instead of kfree() to free an skb.

Fixes: 362899b8 ("macvtap: switch to use skb array")
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/macvtap.c

@@ -536,7 +536,7 @@ static void macvtap_sock_destruct(struct sock *sk)
 	struct sk_buff *skb;
 
 	while ((skb = skb_array_consume(&q->skb_array)) != NULL)
-		kfree(skb);
+		kfree_skb(skb);
 }
 
 static int macvtap_open(struct inode *inode, struct file *file)