A device's DT node or its OPP nodes can contain a phandle to other
device's OPP node, in the "required-opps" property.
This patch implements a routine to find that required OPP from the node
that contains the "required-opps" property.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>