ARM: remove redundant 'select GENERIC_GPIO'

In drivers/gpio/Kcong, ARCH_REQUIRE_GPIOLIB selects GPIOLIB which in
turn selects GENERIC_GPIO.  So GENERIC_GPIO will be selected
automatically for those platforms that select ARCH_REQUIRE_GPIOLIB.

Remove the redundant 'select GENERIC_GPIO' for platforms that already
select ARCH_REQUIRE_GPIOLIB at either mach or plat level.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>