dt-bindings: thermal: thermal-idle: Fix example paths

The reference by path (&{/cpus/cpu@101/thermal-idle}) in the example causes
an error with new version of dtc:

FATAL ERROR: Can't generate fixup for reference to path &{/cpus/cpu@100/thermal-idle}

This is because the examples are built as an overlay and absolute paths
are not valid as references must be by label. The path was also not
resolvable because, by default, examples are placed under 'example-N'
nodes.

As the example contains top-level nodes, the root node must be explicit for
the example to be extracted as-is. This changes the indentation for the
whole example, but the existing indentation is a mess of of random amounts.
Clean this up to be 4 spaces everywhere.

Link: https://lore.kernel.org/r/20221111162729.3381835-1-robh@kernel.org


Signed-off-by: Rob Herring <robh@kernel.org>