ARM: dts: r8a73a4: Fix W=1 dtc warnings

Warning (unit_address_vs_reg): Node /cache-controller@0 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /cache-controller@1 has a unit name, but no reg property

Move the cache-controller nodes under the cpus node, and make their
unit names and reg properties match the MPIDR values.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>