PM: sleep: Print driver flags for all devices during suspend/resume

Currently there are 4 driver flags to control system suspend/resume
behavior: DPM_FLAG_NO_DIRECT_COMPLETE, DPM_FLAG_SMART_PREPARE,
DPM_FLAG_SMART_SUSPEND and DPM_FLAG_MAY_SKIP_RESUME.

Print these flags during suspend/resume so as to get a brief
understanding of the expected behavior of each device, and to
facilitate suspend/resume debugging/tuning.

To enable this tracing:
echo 'file drivers/base/power/main.c +p' >
/sys/kernel/debug/dynamic_debug/control

Signed-off-by: Chen Yu <yu.c.chen@intel.com>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: yu-chen-surf

drivers/base/power/main.c

@@ -441,9 +441,9 @@ static pm_callback_t pm_noirq_op(const struct dev_pm_ops *ops, pm_message_t stat
 
 static void pm_dev_dbg(struct device *dev, pm_message_t state, const char *info)
 {
-	dev_dbg(dev, "%s%s%s\n", info, pm_verb(state.event),
+	dev_dbg(dev, "%s%s%s driver flags: %x\n", info, pm_verb(state.event),
 		((state.event & PM_EVENT_SLEEP) && device_may_wakeup(dev)) ?
-		", may wakeup" : "");
+		", may wakeup" : "", dev->power.driver_flags);
 }
 
 static void pm_dev_err(struct device *dev, pm_message_t state, const char *info,