This adds documentation of device tree bindings for the
STM32 USART
Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Signed-off-by: Alexandre TORGUE <alexandre.torgue@st.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>