dt-bindings: document the STM32 RTC bindings

This patch adds documentation of device tree bindings for the STM32 RTC.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
1 file changed