clk: mediatek: clk-mux: Propagate struct device for mtk-mux

Like done for other clocks, propagate struct device for mtk mux clocks
registered through clk-mux helpers to enable runtime pm support.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: Miles Chen <miles.chen@mediatek.com>
Link: https://lore.kernel.org/r/20230120092053.182923-7-angelogioacchino.delregno@collabora.com


Tested-by: Mingming Su <mingming.su@mediatek.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>