arm64: dts: renesas: r8a77970: Group tuples in thermal reg property

To improve human readability and enable automatic validation, the tuples
in "reg" properties should be grouped.

Fix this by grouping the tuples in the thermal node's "reg" property
using angle brackets.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20191213164115.3697-9-geert+renesas@glider.be


Reviewed-by: Ulrich Hecht <uli+renesas@fpond.eu>