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: NFabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: NAlexandre Torgue <alexandre.torgue@st.com>

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";
 			};
 		};