PM / QoS: Prepare device structure for adding more constraint types

Currently struct dev_pm_info contains only one PM QoS constraints
pointer reserved for latency requirements.  Since one more device
constraints type (i.e. flags) will be necessary, introduce a new
structure, struct dev_pm_qos, that eventually will contain all of
the available device PM QoS constraints and replace the "constraints"
pointer in struct dev_pm_info with a pointer to the new structure
called "qos".

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Jean Pihet <j-pihet@ti.com>
diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
index 9924ea1..30e9ad7 100644
--- a/include/linux/pm_qos.h
+++ b/include/linux/pm_qos.h
@@ -57,6 +57,10 @@
 	struct blocking_notifier_head *notifiers;
 };
 
+struct dev_pm_qos {
+	struct pm_qos_constraints latency;
+};
+
 /* Action requested to pm_qos_update_target */
 enum pm_qos_req_action {
 	PM_QOS_ADD_REQ,		/* Add a new request */