Move this enum to rtc-s5m.c once it is meaningless to others drivers [1].

[1] https://marc.info/?l=linux-rtc&m=152060068925948&w=2Suggested-by: NKrzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: NKrzysztof Kozlowski <krzk@kernel.org>
Acked-by: NLee Jones <lee.jones@linaro.org>
Signed-off-by: NAlexandre Belloni <alexandre.belloni@bootlin.com>