dt-bindings: clock: mediatek: Add new bindings of MediaTek frequency hopping

dt-bindings: clock: mediatek: Add new bindings of MediaTek frequency hopping

Add the new binding documentation for MediaTek frequency hopping
and spread spectrum clocking control.

Co-developed-by: Edward-JW Yang <edward-jw.yang@mediatek.com>
Signed-off-by: Edward-JW Yang <edward-jw.yang@mediatek.com>
Signed-off-by: Johnson Wang <johnson.wang@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20221121122957.21611-3-johnson.wang@mediatek.com
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>