clk: mediatek: add separate gates_offs for cg gates

clk: mediatek: add separate gates_offs for cg gates

Add a gates_offs field to struct mtk_cg_priv and use that instead of
struct mtk_clk_tree.gates_offs.

Prior to this change, struct mtk_clk_tree.gates_offs could be the offset
of struct mtk_clk_tree.gates or struct mtk_cg_priv.gates depending on
the context. This was confusing and error-prone. For example, in mt8365
there is one set of gates that needs an offset and one that does not
that share the same struct mtk_clk_tree. This is fixed in this patch by
giving the correct offset for each gate separately.

Signed-off-by: David Lechner <dlechner@baylibre.com>