clk: mediatek: clk-mt8195-topckgen: Add GPU clock mux notifier

Following the changes done to MT8183, register a similar notifier
for MT8195 as well, allowing safe clockrate updates for the MFGPLL.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Miles Chen <miles.chen@mediatek.com>
Link: https://lore.kernel.org/r/20220927101128.44758-8-angelogioacchino.delregno@collabora.com


Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>