dt-bindings: thermal: k3-j72xx: elaborate on binding description

Elaborate on the function of this device node as well as some of the
properties this node uses.

Signed-off-by: Bryan Brattlof <bb@ti.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20221031232702.10339-6-bb@ti.com


Signed-off-by: Daniel Lezcano <daniel.lezcano@kernel.org>