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

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

[ Upstream commit 22925af785fa3470efdf566339616d801119d348 ]

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

Fixes: ae457b7679c4 ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>