ARM: dts: stm32: Add missing reset-cells node in stm32f746

rcc node must include reset-cells node.
Signed-off-by: NLionel Debieve <lionel.debieve@st.com>
Signed-off-by: NAlexandre TORGUE <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32f746.dtsi

@@ -371,6 +371,7 @@
 		};
 
 		rcc: rcc@40023800 {
+			#reset-cells = <1>;
 			#clock-cells = <2>;
 			compatible = "st,stm32f746-rcc", "st,stm32-rcc";
 			reg = <0x40023800 0x400>;