clk: mediatek: Make mtk_clk_register_composite() static

mtk_clk_register_composite() is not used anywhere outside of the file it
is defined.

Make it static.

Fixes: 9741b1a680 ("clk: mediatek: Add initial common clock support for Mediatek SoCs.")
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: Miles Chen <miles.chen@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: Miles Chen <miles.chen@mediatek.com>
Link: https://lore.kernel.org/r/20220519071610.423372-2-wenst@chromium.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/mediatek/clk-mtk.c

@@ -183,7 +183,7 @@ void mtk_clk_unregister_factors(const struct mtk_fixed_factor *clks, int num,
 }
 EXPORT_SYMBOL_GPL(mtk_clk_unregister_factors);
 
-struct clk *mtk_clk_register_composite(const struct mtk_composite *mc,
+static struct clk *mtk_clk_register_composite(const struct mtk_composite *mc,
 		void __iomem *base, spinlock_t *lock)
 {
 	struct clk *clk;

drivers/clk/mediatek/clk-mtk.h

@@ -147,9 +147,6 @@ struct mtk_composite {
 		.flags = 0,						\
 	}
 
-struct clk *mtk_clk_register_composite(const struct mtk_composite *mc,
-		void __iomem *base, spinlock_t *lock);
-
 int mtk_clk_register_composites(const struct mtk_composite *mcs, int num,
 				void __iomem *base, spinlock_t *lock,
 				struct clk_onecell_data *clk_data);