linux-phytec-ti

PM / OPP: Expose _of_get_opp_desc_node as dev_pm_opp API

Move _of_get_opp_desc_node into include/linux/pm_opp.h and rename it
dev_pm_opp_of_get_opp_desc_node to allow other drivers, such as platform
OPP and cpufreq drivers, to make use of it.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>