clk: rockchip: include downstream muxes into fractional dividers

Use the newly introduced possibility to combine the fractional dividers
with their downstream muxes for all fractional dividers on currently
supported Rockchip SoCs.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Reviewed-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Signed-off-by: Michael Turquette <mturquette@baylibre.com>