s3c rtc driver: add support for S3C64xx

Add support for the S3C64xx SoC to the generic S3C RTC driver.

Signed-off-by: Maurus Cuelenaere <mcuelenaere@gmail.com>
Acked-by: Ben Dooks <ben-linux@fluff.org>
Cc: Frans Pop <elendil@planet.nl>
Cc: Paul Gortmaker <p_gortmaker@yahoo.com>
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>