ARM: dts: stm32: fix a typo for DAC io-channel-cells on stm32h743

Fix a typo on STM32H743 DAC, e.g. s/channels/channel

Fixes: 1536dec4 ("ARM: dts: stm32: Add DAC support on stm32h743")
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32h743.dtsi

@@ -180,14 +180,14 @@ dac: dac@40007400 {
 
 			dac1: dac@1 {
 				compatible = "st,stm32-dac";
-				#io-channels-cells = <1>;
+				#io-channel-cells = <1>;
 				reg = <1>;
 				status = "disabled";
 			};
 
 			dac2: dac@2 {
 				compatible = "st,stm32-dac";
-				#io-channels-cells = <1>;
+				#io-channel-cells = <1>;
 				reg = <2>;
 				status = "disabled";
 			};