clk: mediatek: clk-mtk: Add MUX_DIV_GATE macro

clk: mediatek: clk-mtk: Add MUX_DIV_GATE macro

On MT8196, some clocks use one register for parent selection and
gating, and a separate register for frequency division. Since composite
clocks can combine a mux, divider, and gate in a single entity, add a
macro to simplify registration of such clocks by combining parent
selection, frequency scaling, and enable control into one definition.

Reviewed-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Signed-off-by: Laura Nao <laura.nao@collabora.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>