net/hyperv: fix wrong length of mac address

This patch fixed wrong mac length, it should be ETH_ALEN,
also replaced the hardcode 6 in hyperv_net.h
Signed-off-by: Amos Kong <kongjianjun@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/hyperv/hyperv_net.h

@@ -84,7 +84,7 @@ struct hv_netvsc_packet {
 };
 
 struct netvsc_device_info {
-	unsigned char mac_adr[6];
+	unsigned char mac_adr[ETH_ALEN];
 	bool link_state;	/* 0 - link up, 1 - link down */
 	int  ring_size;
 };

drivers/net/hyperv/netvsc_drv.c

@@ -349,7 +349,7 @@ static int netvsc_set_mac_addr(struct net_device *ndev, void *p)
 	struct net_device_context *ndevctx = netdev_priv(ndev);
 	struct hv_device *hdev =  ndevctx->device_ctx;
 	struct sockaddr *addr = p;
-	char save_adr[14];
+	char save_adr[ETH_ALEN];
 	unsigned char save_aatype;
 	int err;