rtc: s5m: add support for S2MPS14 RTC

rtc: s5m: add support for S2MPS14 RTC

Add support for S2MPS14 to the rtc-s5m driver.  Differences in S2MPS14
(in comparison to S5M8767):

 - Layout of registers
 - Lack of century support for time and alarms (7 registers used for
   storing time/alarm)
 - Two buffer control registers: WUDR and RUDR
 - No register for enabling writing time
 - RTC interrupts are reported in main PMIC I2C device

Signed-off-by: Krzysztof Kozlowski <[email protected]>
Cc: Kyungmin Park <[email protected]>
Cc: Lee Jones <[email protected]>
Cc: Alessandro Zummo <[email protected]>
Cc: Sangbeom Kim <[email protected]>
Cc: Samuel Ortiz <[email protected]>
Cc: Marek Szyprowski <[email protected]>
Cc: Bartlomiej Zolnierkiewicz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>