gpio: pcie-idio-24: Fix port memory offset for get_multiple/set_multiple callbacks

The ioread8/iowrite8 functions expect a memory offset argument. This
patch fixes the ports array to provide the memory addresses of the
respective device I/O registers.

Fixes: ca370815 ("gpio: pcie-idio-24: Implement get_multiple/set_multiple callbacks")
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>