net/hsr: Remove unused but set variable

Remove the unused but set variable master_dev in check_local_dest to fix
the following GCC warning when building with 'W=1':

  net/hsr/hsr_forward.c: In function ‘check_local_dest’:
  net/hsr/hsr_forward.c:303:21: warning: variable ‘master_dev’ set but not used [-Wunused-but-set-variable]
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/hsr/hsr_forward.c

@@ -300,10 +300,6 @@ static void hsr_forward_do(struct hsr_frame_info *frame)
 static void check_local_dest(struct hsr_priv *hsr, struct sk_buff *skb,
 			     struct hsr_frame_info *frame)
 {
-	struct net_device *master_dev;
-
-	master_dev = hsr_port_get_hsr(hsr, HSR_PT_MASTER)->dev;
-
 	if (hsr_addr_is_self(hsr, eth_hdr(skb)->h_dest)) {
 		frame->is_local_exclusive = true;
 		skb->pkt_type = PACKET_HOST;