clk: mediatek: clk-mt7986-topckgen: Properly keep some clocks enabled

Instead of calling clk_prepare_enable() on a bunch of clocks at probe
time, set the CLK_IS_CRITICAL flag to the same as these are required
to be always on, and this is the right way of achieving that.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: Miles Chen <miles.chen@mediatek.com>
Link: https://lore.kernel.org/r/20230120092053.182923-23-angelogioacchino.delregno@collabora.com


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