PM / OPP rename 'head' as 'rcu_head' or 'srcu_head' based on its type
PM / OPP rename 'head' as 'rcu_head' or 'srcu_head' based on its type

Both 'struct dev_pm_opp' and 'struct device_opp' have member with name 'head'
but with different types. This leads to confusion while reading the code.

Name them 'rcu_head' and 'srcu_head'.

Signed-off-by: Viresh Kumar <5ff32272b3d9f86512eddc8e0af523fc6f7924e5@linaro.org>
Signed-off-by: Rafael J. Wysocki <27ffc44a8ec6a212fba98cfc3246c6ce8ab131e0@intel.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs