ARM: s5p: cut the custom ARCH_NR_GPIOS definition

The number of GPIOs defined for the different S5P platforms using
the tricky #define macros are actually as follows:

S5P64x0: 180 GPIOs
S5PC100: 115 GPIOs
S5PV210: 252 GPIOs

The include file <asm-generic/gpio.h> will automatically bump us
to 256 GPIOs which is a nice default value that happens to encompass
all the S5P platform requirements under its roof.

Cut ARCH_NR_GPIOS and the custom spacing macro for extra GPIOs
that is not used anywhere in the kernel.

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