qcacld-3.0: Refine the extscan start BSSID hotlist logic

Make the following updates to the extscan start BSSID hotlist logic:
1) Exclusively use the Unified WMI data structures.
2) Use the new wmi_unified_extscan_start_hotlist_monitor_cmd() API.
3) Update the HDD<=>SME interface to enforce the contract that SME
   must not make any assumptions about the buffers provided by HDD.

Change-Id: I4d9f982177bc61a751ba0e7437fe55482dfd2723
CRs-Fixed: 2291946
diff --git a/core/wma/src/wma_main.c b/core/wma/src/wma_main.c
index 21decf7..0c1b4f7 100644
--- a/core/wma/src/wma_main.c
+++ b/core/wma/src/wma_main.c
@@ -8149,8 +8149,7 @@
 		qdf_mem_free(msg->bodyptr);
 		break;
 	case WMA_EXTSCAN_SET_BSSID_HOTLIST_REQ:
-		wma_extscan_start_hotlist_monitor(wma_handle,
-			(tSirExtScanSetBssidHotListReqParams *) msg->bodyptr);
+		wma_extscan_start_hotlist_monitor(wma_handle, msg->bodyptr);
 		qdf_mem_free(msg->bodyptr);
 		break;
 	case WMA_EXTSCAN_RESET_BSSID_HOTLIST_REQ: