arm64: dts: renesas: Remove unneeded status from thermal nodes

The thermal device is supposed to be always enabled.  As the default
value of the status property is "okay", there is no need to make this
explicit in SoC-specific .dtsi files where no override is involved.

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