drivers/rtc/rtc-s3c.c: fix return value in s3c_rtc_probe()

Return the value returned by platform_get_irq() instead of -ENOENT;

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>