qcacld-3.0: Refine the extscan stop scan logic

Make the following updates to the extscan stop scan logic:
1) Exclusively use the Unified WMI data structures.
2) Update the HDD<=>SME interface to enforce the contract that SME
   must not make any assumptions about the buffers provided by HDD.

Change-Id: Ie4a693b4a91d728a075cffad3ee368b22d9c5b2a
CRs-Fixed: 2335647
diff --git a/core/wma/inc/wma_internal.h b/core/wma/inc/wma_internal.h
index 3736fde..a31df49 100644
--- a/core/wma/inc/wma_internal.h
+++ b/core/wma/inc/wma_internal.h
@@ -368,8 +368,17 @@
 QDF_STATUS wma_start_extscan(tp_wma_handle wma,
 			     struct wifi_scan_cmd_req_params *pstart);
 
+/**
+ * wma_stop_extscan() - stop extscan command to fw.
+ * @wma: wma handle
+ * @params: stop scan command request params
+ *
+ * This function sends stop extscan request to fw.
+ *
+ * Return: QDF Status.
+ */
 QDF_STATUS wma_stop_extscan(tp_wma_handle wma,
-			    tSirExtScanStopReqParams *pstopcmd);
+			    struct extscan_stop_req_params *params);
 
 /**
  * wma_extscan_start_hotlist_monitor() - start hotlist monitor