qcacmn: Fix DP trace logging during HDD Tx timeout

Currently on a HDD Tx timeout, we are recording the event in DP Trace
framework. Currently the framework is unable to handle calls where skb
is NULL.
Add code to handle cases in qdf_dp_trace where the skb could be NULL.

Change-Id: I4d04cd59f11f19c4ba81219925c7f3011c97de29
CRs-Fixed: 1083941

qdf/linux/src/qdf_trace.c

@@ -1586,7 +1586,8 @@ void qdf_dp_trace(qdf_nbuf_t nbuf, enum QDF_DP_TRACE_ID code,
 	if (qdf_dp_enable_check(nbuf, code, dir) == false)
 		return;
 
-	qdf_dp_add_record(code, data, size, QDF_NBUF_CB_DP_TRACE_PRINT(nbuf));
+	qdf_dp_add_record(code, data, size,
+		(nbuf != NULL) ? QDF_NBUF_CB_DP_TRACE_PRINT(nbuf) : false);
 }
 EXPORT_SYMBOL(qdf_dp_trace);