ARM: dts: stm32: add PWM and triggers on stm32mp157c-ev1 board

stm32mp157c evaluation board has TIM2_CH4, TIM8_CH4 and TIM12_CH1
available on GPIO expansion connector.
Add PWM and associated triggers (for ADC/DAC) on these timers.
Keep them disabled so these pins can be used as GPIOs by default.
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32mp157c-ev1.dts

@@ -19,3 +19,39 @@ aliases {
 		serial0 = &uart4;
 	};
 };
+
+&timers2 {
+	status = "disabled";
+	pwm {
+		pinctrl-0 = <&pwm2_pins_a>;
+		pinctrl-names = "default";
+		status = "okay";
+	};
+	timer@1 {
+		status = "okay";
+	};
+};
+
+&timers8 {
+	status = "disabled";
+	pwm {
+		pinctrl-0 = <&pwm8_pins_a>;
+		pinctrl-names = "default";
+		status = "okay";
+	};
+	timer@7 {
+		status = "okay";
+	};
+};
+
+&timers12 {
+	status = "disabled";
+	pwm {
+		pinctrl-0 = <&pwm12_pins_a>;
+		pinctrl-names = "default";
+		status = "okay";
+	};
+	timer@11 {
+		status = "okay";
+	};
+};