[ARM] 3915/1: S3C2412: Add s3c2410_gpio_getirq() to general gpio.c

s3c2410_gpio_getirq() holds for the S3C2412 build,
so ensure that it gets built for all the current
S3C24XX architectures

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>