at1700: fix double free_irq

free_irq() is called both in net_close() and cleanup_card().  Since it
is requested in at1700_probe1(), leave free_irq() only in cleanup_card()
for balance.

Signed-off-by: Kulikov Vasiliy <segooon@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>