rtc: s3c: add s3c_rtc_data structure to use variant data instead of s3c_cpu_type

Add s3c_rtc_data structure to variant data according to SoC type.  The
s3c_rtc_data structure includes some functions to control RTC operation
and specific data dependent on SoC type.
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>