st/omx/enc: check uninitialized list from task release

The uninitialized list should be checked and returned.

Thank Julien for the notification and suggested fix.

Signed-off-by: Leo Liu <leo.liu@amd.com>
Cc: "12.0" <mesa-stable@lists.freedesktop.org>

src/gallium/state_trackers/omx/vid_enc.c

@@ -874,8 +874,8 @@ static void enc_ReleaseTasks(struct list_head *head)
 {
    struct encode_task *i, *next;
 
-   if (!head)
-	   return;
+   if (!head || !head->next)
+      return;
 
    LIST_FOR_EACH_ENTRY_SAFE(i, next, head, list) {
       pipe_resource_reference(&i->bitstream, NULL);