notifier: add notifier free support

To power down a secondary core gracefully, we need to free the notifier
related memory used on the corresponding core cleanly, which will help
to create clean one on the next powering up to the core.

Signed-off-by: Keyon Jie <yang.jie@linux.intel.com>

Author: keyonjie

src/lib/notifier.c

@@ -189,7 +189,7 @@ void init_system_notify(struct sof *sof)
 {
 	struct notify **notify = arch_notify_get();
 	int i;
-	*notify = rzalloc(SOF_MEM_ZONE_SYS, 0, SOF_MEM_CAPS_RAM,
+	*notify = rzalloc(SOF_MEM_ZONE_SYS_RUNTIME, 0, SOF_MEM_CAPS_RAM,
 			  sizeof(**notify));
 
 	spinlock_init(&(*notify)->lock);
@@ -203,4 +203,7 @@ void init_system_notify(struct sof *sof)
 
 void free_system_notify(void)
 {
+	struct notify **notify = arch_notify_get();
+
+	rfree(*notify);
 }