ARM: amba: ux500: get rid of NO_IRQ

irq 0 now means no irq, so get rid of this unnecessary initializer.

Acked-by: srinidhi kasagar <srinidhi.kasagar@stericsson.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>