gpio: 104-idi-48: Allow IRQ sharing

The ACCES 104-IDI-48 can differentiate between its own and other
devices' interrupt requests. Therefore, IRQ sharing is possible and
should be permitted.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>