arm: pxa: tosa: do not use gpiochip_reserve()

GPIO address space reservation during early platform initialization is
not needed anymore for Tosa. Remove the calls to gpiochip_reserve()
which is due to be removed.

Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>