Merge tag 'clk-2022.04-rc2' of https://source.denx.de/u-boot/custodians/u-boot-clk

Clock patches for v2022.04-rc2

This has an assortment of cleanups and the occasional bugfix. Also present
is the addition of the clock subsystem documentation to HTML docs.

CI: https://source.denx.de/u-boot/custodians/u-boot-clk/-/pipelines/11075