drivers/net/usb: Correct code taking the size of a pointer

sizeof(dev->dev_addr) is the size of a pointer.  A few lines above, the
size of this field is obtained using netdev->addr_len for a call to memcpy,
so do the same here.

A simplified version of the semantic patch that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@@
expression *x;
expression f;
type T;
@@

*f(...,(T)x,...)
// </smpl>
Signed-off-by: NJulia Lawall <julia@diku.dk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/usb/rtl8150.c

@@ -324,7 +324,7 @@ static int rtl8150_set_mac_address(struct net_device *netdev, void *p)
 		dbg("%02X:", netdev->dev_addr[i]);
 	dbg("%02X\n", netdev->dev_addr[i]);
 	/* Set the IDR registers. */
-	set_registers(dev, IDR, sizeof(netdev->dev_addr), netdev->dev_addr);
+	set_registers(dev, IDR, netdev->addr_len, netdev->dev_addr);
 #ifdef EEPROM_WRITE
 	{
 	u8 cr;