clk: mediatek: mt8173: Remove mtk_clk_enable_critical()

clk: mediatek: mt8173: Remove mtk_clk_enable_critical()

The entire point of mtk_clk_enable_critical() is to raise the refcount
of some clocks so that they won't be turned off during runtime, but
this is the same as what the CLK_IS_CRITICAL flag does.

Set CLK_IS_CRITICAL on all of the critical clocks and remove the
aforementioned function as a cleanup.

No functional changes.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://lore.kernel.org/r/20230120092053.182923-10-angelogioacchino.delregno@collabora.com
Tested-by: Mingming Su <mingming.su@mediatek.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>