arm64: dts: meson-sm1: add cpu thermal nodes

Add thermal nodes for the Amlogic SM1 SoCs based on the G12A and G12B
thermal nodes.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Link: https://lore.kernel.org/r/20200512093916.19676-3-narmstrong@baylibre.com