dt-bindings: opp: v2-qcom-level: Let qcom,opp-fuse-level be a 2-long array

In some instances (particularly with CPRh) we might want to specifiy
more than one qcom,opp-fuse-level, as the same OPP subnodes may be
used by different "CPR threads". We need to make sure that
n = num_threads entries is legal and so far nobody seems to use more
than two, so let's allow that.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>