qcacmn: Add unregister API for direct buf ring

Add Unregister API to de-register and free resources in direct buf
module. Existing logic of freeing all resources as part of pdev destroy
does not take care of soc_start and soc_stop scenarios. Add this API to
enable modules to de-register as part of soc_stop and register during
start.

CRs-Fixed: 2385313
Change-Id: Ibe6f6bc5f4bd2acc5a9fe71eee09c151853073bc

spectral/dispatcher/inc/wlan_spectral_tgt_api.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2018 The Linux Foundation. All rights reserved.
+ * Copyright (c) 2017-2019 The Linux Foundation. All rights reserved.
  *
  *
  * Permission to use, copy, modify, and/or distribute this software for
@@ -232,7 +232,7 @@ tgt_spectral_process_report(struct wlan_objmgr_pdev *pdev,
 			    void *payload);
 
 /**
- * tgt_spectral_register_to_dbr() - Register to direct dma
+ * tgt_spectral_register_to_dbr() - Register to direct DMA
  * @pdev: Pointer to pdev object
  *
  * Return: QDF_STATUS
@@ -240,6 +240,15 @@ tgt_spectral_process_report(struct wlan_objmgr_pdev *pdev,
 QDF_STATUS
 tgt_spectral_register_to_dbr(struct wlan_objmgr_pdev *pdev);
 
+/**
+ * tgt_spectral_unregister_to_dbr() - Register to direct DMA
+ * @pdev: Pointer to pdev object
+ *
+ * Return: QDF_STATUS
+ */
+QDF_STATUS
+tgt_spectral_unregister_to_dbr(struct wlan_objmgr_pdev *pdev);
+
 /**
  * tgt_spectral_get_target_type() - Get target type
  * @psoc: Pointer to psoc object