ARM: dts: STiH407-family: Add missing pwm irq

Add the missing interrupt node to properly probe
the pwm device.

This fix following error log :
[    0.208119] sti-pwm 9510000.pwm: Failed to obtain IRQ
[    0.222352] pwm-regulator pwm-regulator: Failed to get PWM: -517
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Signed-aff-by: Patrice CHOTARD <patrice.chotard@st.com>

arch/arm/boot/dts/stih407-family.dtsi

@@ -688,6 +688,7 @@ pwm1: pwm@9510000 {
 			compatible	= "st,sti-pwm";
 			#pwm-cells	= <2>;
 			reg		= <0x9510000 0x68>;
+			interrupts      = <GIC_SPI 131 IRQ_TYPE_NONE>;
 			pinctrl-names	= "default";
 			pinctrl-0	= <&pinctrl_pwm1_chan0_default
 					&pinctrl_pwm1_chan1_default