dt-bindings: clock: u8500: Rewrite in YAML and extend

This rewrites the ux500/u8500 clock bindings in YAML schema and extends them
with the PRCC reset controller.

The bindings are a bit idiomatic but it just reflects their age, the ux500
platform was used as guinea pig for early device tree conversion of platforms
in 2015. The new subnode for the reset controller follows the pattern of the
old bindings and adds a node with reset-cells for this.

Cc: devicetree@vger.kernel.org
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20210921184803.1757916-1-linus.walleij@linaro.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>