arm64: dts: mt7986: add PWM to BPI-R3

Add pwm node and pinctrl to BananaPi R3 devicetree.
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Link: https://lore.kernel.org/r/20230421132047.42166-6-linux@fw-web.deSigned-off-by: Matthias Brugger <matthias.bgg@gmail.com>

arch/arm64/boot/dts/mediatek/mt7986a-bananapi-bpi-r3.dts

@@ -275,6 +275,13 @@ mux {
 		};
 	};
 
+	pwm_pins: pwm-pins {
+		mux {
+			function = "pwm";
+			groups = "pwm0", "pwm1_0";
+		};
+	};
+
 	spi_flash_pins: spi-flash-pins {
 		mux {
 			function = "spi";
@@ -345,6 +352,12 @@ mux {
 	};
 };
 
+&pwm {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pwm_pins>;
+	status = "okay";
+};
+
 &spi0 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&spi_flash_pins>;