Add a binding for the STMicroelectronics STM32 IPCC block exposing a
mailbox mechanism between two processors.
Signed-off-by: NFabien Dessenne <fabien.dessenne@st.com>
Signed-off-by: NLudovic Barre <ludovic.barre@st.com>
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NJassi Brar <jaswinder.singh@linaro.org>