PEL: Add license prologue to source files

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I31b12f509d32b79064a8a427af35e6a310273051
diff --git a/extensions/openpower-pels/private_header.cpp b/extensions/openpower-pels/private_header.cpp
index 64b1f2c..4f18ab7 100644
--- a/extensions/openpower-pels/private_header.cpp
+++ b/extensions/openpower-pels/private_header.cpp
@@ -1,3 +1,18 @@
+/**
+ * Copyright © 2019 IBM Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 #include "private_header.hpp"
 
 #include "log_id.hpp"