ksz884x: don't copy too much in netdev_set_mac_address()

MAX_ADDR_LEN is 32.  ETH_ALEN is 6.  mac->sa_data is a 14 byte array, so
the memcpy() is doing a read past the end of the array.  I asked about
this on netdev and Ben Hutchings told me it's supposed to be copying
ETH_ALEN bytes (thanks Ben).

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/micrel/ksz884x.c

@@ -5675,7 +5675,7 @@ static int netdev_set_mac_address(struct net_device *dev, void *addr)
 		memcpy(hw->override_addr, mac->sa_data, ETH_ALEN);
 	}
 
-	memcpy(dev->dev_addr, mac->sa_data, MAX_ADDR_LEN);
+	memcpy(dev->dev_addr, mac->sa_data, ETH_ALEN);
 
 	interrupt = hw_block_intr(hw);