net/packet: remove redundant initialization of variable err

The variable err is being initialized with a value that is never read
and it is being updated later with a new value.  The initialization is
redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/packet/af_packet.c

@@ -4293,7 +4293,7 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
 	struct packet_ring_buffer *rb;
 	struct sk_buff_head *rb_queue;
 	__be16 num;
-	int err = -EINVAL;
+	int err;
 	/* Added to avoid minimal code churn */
 	struct tpacket_req *req = &req_u->req;