PM: QoS: Restore support for default value on frequency QoS

Commit 8d366942 ("PM: QoS: Add check to make sure CPU freq is
non-negative") makes sure CPU freq is non-negative to avoid negative
value converting to unsigned data type. However, when the value is
PM_QOS_DEFAULT_VALUE, pm_qos_update_target specifically uses
c->default_value which is set to FREQ_QOS_MIN/MAX_DEFAULT_VALUE when
cpufreq_policy_alloc is executed, for this case handling.

Adding check for PM_QOS_DEFAULT_VALUE to let default setting work will
fix this problem.

Fixes: 8d366942 ("PM: QoS: Add check to make sure CPU freq is non-negative")
Link: https://lore.kernel.org/lkml/20230626035144.19717-1-Chung-kai.Yang@mediatek.com/
Link: https://lore.kernel.org/lkml/20230627071727.16646-1-Chung-kai.Yang@mediatek.com/
Link: https://lore.kernel.org/lkml/CAJZ5v0gxNOWhC58PHeUhW_tgf6d1fGJVZ1x91zkDdht11yUv-A@mail.gmail.com/Signed-off-by: Chungkai Yang <Chung-kai.Yang@mediatek.com>
Cc: 6.0+ <stable@vger.kernel.org> # 6.0+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

kernel/power/qos.c

@@ -426,6 +426,11 @@ late_initcall(cpu_latency_qos_init);
 
 /* Definitions related to the frequency QoS below. */
 
+static inline bool freq_qos_value_invalid(s32 value)
+{
+	return value < 0 && value != PM_QOS_DEFAULT_VALUE;
+}
+
 /**
  * freq_constraints_init - Initialize frequency QoS constraints.
  * @qos: Frequency QoS constraints to initialize.
@@ -531,7 +536,7 @@ int freq_qos_add_request(struct freq_constraints *qos,
 {
 	int ret;
 
-	if (IS_ERR_OR_NULL(qos) || !req || value < 0)
+	if (IS_ERR_OR_NULL(qos) || !req || freq_qos_value_invalid(value))
 		return -EINVAL;
 
 	if (WARN(freq_qos_request_active(req),
@@ -563,7 +568,7 @@ EXPORT_SYMBOL_GPL(freq_qos_add_request);
  */
 int freq_qos_update_request(struct freq_qos_request *req, s32 new_value)
 {
-	if (!req || new_value < 0)
+	if (!req || freq_qos_value_invalid(new_value))
 		return -EINVAL;
 
 	if (WARN(!freq_qos_request_active(req),