arm64: dts: imx8mm-nitrogen-r2: add PWMs

Add description for the four PWMs.
Signed-off-by: Adrien Grassein <adrien.grassein@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mm-nitrogen-r2.dts

@@ -198,6 +198,33 @@ rtc@68 {
 	};
 };
 
+&pwm1 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_pwm1>;
+	status = "okay";
+};
+
+&pwm2 {
+	assigned-clocks = <&clk IMX8MM_CLK_PWM2>;
+	assigned-clock-parents = <&clk IMX8MM_SYS_PLL1_40M>;
+	assigned-clock-rates = <40000000>;
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_pwm2>;
+	status = "okay";
+};
+
+&pwm3 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_pwm3>;
+	status = "okay";
+};
+
+&pwm4 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_pwm4>;
+	status = "okay";
+};
+
 /* BT */
 &uart1 {
 	pinctrl-names = "default";
@@ -354,6 +381,30 @@ MX8MM_IOMUXC_SAI2_RXC_GPIO4_IO22 0x1c0
 		>;
 	};
 
+	pinctrl_pwm1: pwm1grp {
+		fsl,pins = <
+			MX8MM_IOMUXC_SPDIF_EXT_CLK_PWM1_OUT 0x16
+		>;
+	};
+
+	pinctrl_pwm2: pwm2grp {
+		fsl,pins = <
+			MX8MM_IOMUXC_SPDIF_RX_PWM2_OUT 0x16
+		>;
+	};
+
+	pinctrl_pwm3: pwm3grp {
+		fsl,pins = <
+			MX8MM_IOMUXC_SPDIF_TX_PWM3_OUT 0x16
+		>;
+	};
+
+	pinctrl_pwm4: pwm4grp {
+		fsl,pins = <
+			MX8MM_IOMUXC_SAI3_MCLK_PWM4_OUT 0x16
+		>;
+	};
+
 	pinctrl_reg_wlan_vmmc: reg-wlan-vmmcgrp {
 		fsl,pins = <
 			MX8MM_IOMUXC_SAI5_RXC_GPIO3_IO20 0x16