clk: ux500: Convert ABx500 clocks to use OF probing
These clocks have been broken for a long time unfortunately, a
hurdle of misc problems made them stop working at some point
breaking USB and audio on Ux500.
The platform as such and all "regular" clocks are migrated to
OF/device tree, so let's migrate also this driver.
With this patch and the corresponding DTS fixes, and a bunch
of probe deferral fixes, audio starts working again on Ux500.