ARM: do away with final ARCH_REQUIRE_GPIOLIB

A new user of the Kconfig selection of ARCH_REQUIRE_GPIOLIB
has appeared. Replace with just selecting GPIOLIB.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>