qcacld-3.0: Refine the extscan get capabilities logic

Make the following updates to the extscan get capabilities 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: I9e57c86a3da0924af01d82d626b61c28f7d520bf
CRs-Fixed: 2330211
diff --git a/core/wma/src/wma_main.c b/core/wma/src/wma_main.c
index 26d219c..75da6a2 100644
--- a/core/wma/src/wma_main.c
+++ b/core/wma/src/wma_main.c
@@ -8243,8 +8243,7 @@
 		qdf_mem_free(msg->bodyptr);
 		break;
 	case WMA_EXTSCAN_GET_CAPABILITIES_REQ:
-		wma_extscan_get_capabilities(wma_handle,
-			(tSirGetExtScanCapabilitiesReqParams *) msg->bodyptr);
+		wma_extscan_get_capabilities(wma_handle, msg->bodyptr);
 		qdf_mem_free(msg->bodyptr);
 		break;
 	case WMA_SET_EPNO_LIST_REQ: