Add lockdep asserts for holding the dev->power.lock to non-static
functions which require this. They could be used outside of the file so
asserts may help in detecting locking misuse.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>