dt-bindings: arm: cpus: add qcom kryo 360 compatible

The Snapdragon 670 uses CPUs named Kryo 360 silver and Kryo 360 gold.
Add the compatible string in the documentation.

Signed-off-by: Richard Acayan <mailingradian@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221111001818.124901-2-mailingradian@gmail.com