ARM: dts: s5pv210: move PMU node out of clock controller

The Power Management Unit (PMU) is a separate device which has little
common with clock controller.  Moving it to one level up (from clock
controller child to SoC) allows to remove fake simple-bus compatible and
dtbs_check warnings like:

  clock-controller@e0100000: $nodename:0:
    'clock-controller@e0100000' does not match '^([a-z][a-z0-9\\-]+-bus|bus|soc|axi|ahb|apb)(@[0-9a-f]+)?$'

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Tested-by: Jonathan Bakker <xc-racer2@live.ca>
Link: https://lore.kernel.org/r/20200907161141.31034-8-krzk@kernel.org