qcacmn: Fix memory leak during REO cmd ring drain

Fix possible REO descriptor leak while draining REO
command ring by invoking command status handlers with
special error code.

Change-Id: I2fe5f60489b57a4b0a287e67e5610112f7292677

hal/wifi3.0/hal_reo.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017 The Linux Foundation. All rights reserved.
+ * Copyright (c) 2017-2018 The Linux Foundation. All rights reserved.
  *
  * Permission to use, copy, modify, and/or distribute this software for
  * any purpose with or without fee is hereby granted, provided that the
@@ -137,7 +137,8 @@ enum reo_cmd_exec_status {
 	HAL_REO_CMD_SUCCESS = 0,
 	HAL_REO_CMD_BLOCKED = 1,
 	HAL_REO_CMD_FAILED = 2,
-	HAL_REO_CMD_RESOURCE_BLOCKED = 3
+	HAL_REO_CMD_RESOURCE_BLOCKED = 3,
+	HAL_REO_CMD_DRAIN = 0xff
 };
 
 /**