clk: mediatek: add support for gates in clk_tree for infrasys

clk: mediatek: add support for gates in clk_tree for infrasys

Add support for gates in clk_tree for infrasys ops.

Infracfg clks can have a sum of gates and muxes, and current solution
handle this by duplicating the driver and split clks for mux and clks
for gates. Upstream linux kernel handle this differently and doesn't
have this distinction.

To be closer to the upstream kernel clock definition, implement
additional logic to have gates defined in the clk_tree and implement
variant for the infrasys ops to handle gates defined in the tree.

Similar to how it's done with factor and mux, we introduce gates_offs.
Upstream kernel follow the similar logic with all the ID defined as
FDIVS, MUXES and finally GATES.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>