dt-bindings: cpufreq: qcom-cpufreq-nvmem: Document krait-cpu

Document newly introduced operating-points-v2-krait-cpu compatible to
the list of accepted compatible for opp-v2-kryo-cpu nodes.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>