ARM: ux500: Change the type of interrupt to something compatible

On boot the Nomadik GPIO controller complains that an IRQ can't be
configured as active high level-sensitive, so this patch converts
it to be low-to-high edge triggered instead.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>