PM / Runtime: fix recursive locking warning of lockdep from rpm_resume()

For device with no_callbacks flag set, its power lock and its parent's
power lock may be held nestedly in rpm_resume, so we should take
spin_lock_nested(lock, SINGLE_DEPTH_NESTING) to acquire parent power lock
to avoid lockdep warning.
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

drivers/base/power/runtime.c

@@ -503,7 +503,7 @@ static int rpm_resume(struct device *dev, int rpmflags)
 	 * the resume will actually succeed.
 	 */
 	if (dev->power.no_callbacks && !parent && dev->parent) {
-		spin_lock(&dev->parent->power.lock);
+		spin_lock_nested(&dev->parent->power.lock, SINGLE_DEPTH_NESTING);
 		if (dev->parent->power.disable_depth > 0
 		    || dev->parent->power.ignore_children
 		    || dev->parent->power.runtime_status == RPM_ACTIVE) {