mmc: sdhci-s3c: Remove unused define for NUM_GPIOS

NUM_GPIOS is not used after e19499ae

 ("mmc: sdhci-s3c: let device
core setup the default pin configuration").  Thus remove it.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Chris Ball <chris@printf.net>