rtc: add STM32 RTC driver

This patch adds support for the STM32 RTC.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
3 files changed