clk: mediatek: gate: Consolidate gate type clk related code

Right now some bits of the gate type clk code are in clk-gate.[ch], but
other bits are in clk-mtk.[ch]. This is different from the cpumux and
mux type clks, for which all of the code are found in the same files.

Move the functions that register multiple clks from a given list,
mtk_clk_register_gates_with_dev() and mtk_clk_register_gates(), to
clk-gate.[ch] to consolidate all the code for the gate type clks.

This commit only moves code with minor whitespace fixups to correct
the code style. Further improvements, such as internalizing various
functions and structures will be done in later commits.

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>
Link: https://lore.kernel.org/r/20220208124034.414635-3-wenst@chromium.org


Reviewed-by: Chun-Jie Chen <chun-jie.chen@mediatek.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>