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.

Cc: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>