clk: mediatek: mt8135: Properly use CLK_IS_CRITICAL flag

clk: mediatek: mt8135: Properly use CLK_IS_CRITICAL flag

Instead of calling clk_prepare_enable() for clocks that shall stay
enabled, use the CLK_IS_CRITICAL flag, which purpose is exactly that.

Fixes: a8aede794843 ("clk: mediatek: Add basic clocks for Mediatek MT8135.")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://lore.kernel.org/r/20230306140543.1813621-52-angelogioacchino.delregno@collabora.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>