The new Rockchip socs have optional half divider:
The formula is shown as:
freq_out = 2*freq_in / (2*div + 3)
Is this the same for all of new SoCs.
So we use "branch_half_divider" + "COMPOSITE_NOMUX_HALFDIV \
DIV_HALF \ COMPOSITE_HALFDIV \ CMPOSITE_NOGATE_HALFDIV"
to hook that special divider clock-type into our clock-tree.