The S2MPS11 PMIC (present on Arndale Octa board) has the same RTC module
as S2MPS14 device. Add respective mfd cell to enable it.
Change-Id: I2bd04e78884b29bfb871147f1bcd26964c3b5c8d Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> Signed-off-by: Lee Jones <lee.jones@linaro.org>