ARM: at91: fix at91sam9261ek Ethernet dm9000 irq

You need to setup the dm9000 irq via gpio_to_irq() since
d0fbda9a

 (ARM: at91/gpio: drop PIN_BASE).

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: stable <stable@vger.kernel.org>	[3.2+]