r8169: fix early spinlock use

rtl8169_init_one
-> rtl_init_mac_address
   -> rtl_rar_set
      -> spin_lock_irq(&tp->lock);
[...]
-> spin_lock_init(&tp->lock);

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Signed-off-by: David S. Miller <davem@davemloft.net>