arm64: dts: mediatek: mt7622: Add missing pwm-cells to pwm node

Specify #pwm-cells on pwm@11006000 to make it actually usable.

Fixes: ae457b7679 ("arm64: dts: mt7622: add SoC and peripheral related device nodes")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20221128112028.58021-2-angelogioacchino.delregno@collabora.com
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>

arch/arm64/boot/dts/mediatek/mt7622.dtsi

@@ -435,6 +435,7 @@
 	pwm: pwm@11006000 {
 		compatible = "mediatek,mt7622-pwm";
 		reg = <0 0x11006000 0 0x1000>;
+		#pwm-cells = <2>;
 		interrupts = <GIC_SPI 77 IRQ_TYPE_LEVEL_LOW>;
 		clocks = <&topckgen CLK_TOP_PWM_SEL>,
 			 <&pericfg CLK_PERI_PWM_PD>,