qcacmn: Fix possible buffer overflow in send_stats_ext_req_cmd_tlv

In the function __wlan_hdd_cfg80211_stats_ext_request,
data_len is recieved from vendor command and is passed ultimately
to send_stats_ext_req_cmd_tlv.  In send_stats_ext_req_cmd_tlv, len
is calculated as sum of sizeof(*cmd), WMI_TLV_HDR_SIZE,
preq->request_data_len.The len is of type uint16_t
and adding sizeof(*cmd) + WMI_TLV_HDR_SIZE will cause a buffer
overflow.

Changed the datatype of len to size_t so that it doesn't overflow.

Change-Id: I6618042e3c60bbdb1ff5d833188f4bdb4832da7a
CRs-Fixed: 2243169

wmi/src/wmi_unified_tlv.c

@@ -9294,7 +9294,7 @@ static QDF_STATUS send_stats_ext_req_cmd_tlv(wmi_unified_t wmi_handle,
 	QDF_STATUS ret;
 	wmi_req_stats_ext_cmd_fixed_param *cmd;
 	wmi_buf_t buf;
-	uint16_t len;
+	size_t len;
 	uint8_t *buf_ptr;
 
 	len = sizeof(*cmd) + WMI_TLV_HDR_SIZE + preq->request_data_len;