clk: ux500: Add driver for the reset portions of PRCC

The Ux500 PRCC (peripheral reset and clock controller) can also
control reset of the IP blocks, not just clocks. As the PRCC is probed
as a clock controller and we have other platforms implementing combined
clock and reset controllers, follow this pattern and implement the PRCC
rest controller as part of the clock driver.

The reset controller needs to be selected from the machine as Ux500 has
traditionally selected its mandatory subsystem prerequisites from there.

Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20210921184803.1757916-2-linus.walleij@linaro.org
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
[sboyd@kernel.org: Dropped allocation error message]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>