PM / runtime: Update documentation to reflect the current code flow

The runtime PM documentation in runtime_pm.txt has not been updated
after some changes to the system suspend and resume core code, so
update it to reflect the current code flow.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>

Documentation/power/runtime_pm.txt

@@ -648,15 +648,17 @@ The PM core does its best to reduce the probability of race conditions between
 the runtime PM and system suspend/resume (and hibernation) callbacks by carrying
 out the following operations:
 
-  * During system suspend it calls pm_runtime_get_noresume() and
-    pm_runtime_barrier() for every device right before executing the
-    subsystem-level .suspend() callback for it.  In addition to that it calls
-    __pm_runtime_disable() with 'false' as the second argument for every device
-    right before executing the subsystem-level .suspend_late() callback for it.
-
-  * During system resume it calls pm_runtime_enable() and pm_runtime_put()
-    for every device right after executing the subsystem-level .resume_early()
-    callback and right after executing the subsystem-level .resume() callback
+  * During system suspend pm_runtime_get_noresume() is called for every device
+    right before executing the subsystem-level .prepare() callback for it and
+    pm_runtime_barrier() is called for every device right before executing the
+    subsystem-level .suspend() callback for it.  In addition to that the PM core
+    calls  __pm_runtime_disable() with 'false' as the second argument for every
+    device right before executing the subsystem-level .suspend_late() callback
+    for it.
+
+  * During system resume pm_runtime_enable() and pm_runtime_put() are called for
+    every device right after executing the subsystem-level .resume_early()
+    callback and right after executing the subsystem-level .complete() callback
     for it, respectively.
 
 7. Generic subsystem callbacks