PM / OPP: Documentation: Fix opp-microvolt in examples

The triplet present in "opp-microvolt" property should be in the order
<target min max>, while all the examples have it in the order
<min target max>.

Fix it.

Luckily all of the users of "opp-microvolt" property have applied brain
instead of copying the examples from documentation and none of the
actual dts files have it wrong.

Reported-by: Rob Herring <robh@kernel.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>