clk: rockchip: convert manually created factor clocks to the new type

Clean up the init code and move the creation of factor clocks to the
appropriate positions coming from the clock architecture diagrams.

This also unifies the artificial separation of the hclk_vcodec etc clocks
again.

We do keep the separate definition of some watchdog and usb480m pseudo
clocks for now, as they're not real factor clocks from the clock-tree
but placeholders for fixes to come (usb480m gets supplied by the
missing driver for the new usbphy type and the watchdog-gate is sitting
somewhere else together which we cannot model currently).

Signed-off-by: Heiko Stuebner <heiko@sntech.de>