arm64: dts: mediatek: mt7986: drop "#clock-cells" from PWM

arm64: dts: mediatek: mt7986: drop "#clock-cells" from PWM

PWM is not a clock provider and its binding doesn't specify
"#clock-cells" property.

This fixes:
arch/arm64/boot/dts/mediatek/mt7986a-bananapi-bpi-r3.dtb: pwm@10048000: '#clock-cells' does not match any of the regexes: 'pinctrl-[0-9]+'
        from schema $id: http://devicetree.org/schemas/pwm/mediatek,mt2712-pwm.yaml#

Fixes: eabb04df46c6 ("arm64: dts: mt7986: add PWM")
Cc: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/r/20240101182040.28538-1-zajec5@gmail.com
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>