ARM: dts: stm32: update pwm-cells for LPTimer on stm32h743

LPTimer pwm cells should be updated to 3, to allow initialization of
channel, period and polarity.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>
diff --git a/arch/arm/boot/dts/stm32h743.dtsi b/arch/arm/boot/dts/stm32h743.dtsi
index 7b64af0..637beff 100644
--- a/arch/arm/boot/dts/stm32h743.dtsi
+++ b/arch/arm/boot/dts/stm32h743.dtsi
@@ -86,6 +86,7 @@
 
 			pwm {
 				compatible = "st,stm32-pwm-lp";
+				#pwm-cells = <3>;
 				status = "disabled";
 			};
 
@@ -382,6 +383,7 @@
 
 			pwm {
 				compatible = "st,stm32-pwm-lp";
+				#pwm-cells = <3>;
 				status = "disabled";
 			};
 
@@ -408,6 +410,7 @@
 
 			pwm {
 				compatible = "st,stm32-pwm-lp";
+				#pwm-cells = <3>;
 				status = "disabled";
 			};
 
@@ -429,6 +432,7 @@
 
 			pwm {
 				compatible = "st,stm32-pwm-lp";
+				#pwm-cells = <3>;
 				status = "disabled";
 			};
 		};
@@ -444,6 +448,7 @@
 
 			pwm {
 				compatible = "st,stm32-pwm-lp";
+				#pwm-cells = <3>;
 				status = "disabled";
 			};
 		};