clk: mediatek: Add mtk_clk_simple_probe() to simplify clock providers

clk: mediatek: Add mtk_clk_simple_probe() to simplify clock providers

Most of subsystem clock providers only need to register clock gates
in their probe() function.
To reduce the duplicated code by add a generic function.

Signed-off-by: Weiyi Lu <weiyi.lu@mediatek.com>
Signed-off-by: Chun-Jie Chen <chun-jie.chen@mediatek.com>
Link: https://lore.kernel.org/r/20210726105719.15793-9-chun-jie.chen@mediatek.com
Reviewed-by: Ikjoon Jang <ikjn@chromium.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>