soc: mediatek: mmsys: Drop <linux/clk-provider.h>

After the split, the mt8173 MMSYS driver is no longer a clock provider,
and thus does not need to include <linux/clk-provider.h>.

Fixes: 13032709 ("clk / soc: mediatek: Move mt8173 MMSYS to platform driver")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/20200506120204.31422-1-geert+renesas@glider.be


Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>