ARM: dts: renesas: Group tuples in APMU cpus properties

To improve human readability and enable automatic validation, the tuples
in "cpus" properties in device nodes for Advanced Power Management Units
for AP-System Core (APMU) should be grouped using angle brackets.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20210204130517.1647073-2-geert+renesas@glider.be