PM / QoS: Add return code to pm_qos_get_value function.

pm_qos_get_value don't return a return code in all cases. It's sure that
anything interesting happend after BUG() but this prevent any compilation
warning.

[rjw: Chaneged the new return value to PM_QOS_DEFAULT_VALUE.]
Signed-off-by: Luis Gonzalez Fernandez <luisgf@gmail.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

kernel/power/qos.c

@@ -139,6 +139,7 @@ static inline int pm_qos_get_value(struct pm_qos_constraints *c)
 	default:
 		/* runtime check for not using enum */
 		BUG();
+		return PM_QOS_DEFAULT_VALUE;
 	}
 }