dt-bindings: arm: stm32: document lxa,stm32mp157c-mc1 compatible

Document the STM32MP157 based Linux Automation MC-1 device tree
compatible.
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

Documentation/devicetree/bindings/arm/stm32/stm32.yaml

@@ -38,6 +38,7 @@ properties:
       - items:
           - enum:
               - arrow,stm32mp157a-avenger96 # Avenger96
+              - lxa,stm32mp157c-mc1
               - st,stm32mp157c-ed1
               - st,stm32mp157a-dk1
               - st,stm32mp157c-dk2