doxygen: Remove copyright block from Doxygen comments

Remove the copyright block from the Doxygen comments, to clean up the
detailed description in the generated Doxygen output. Also, add \file and
\brief tags to all headers in doxygen/input.
diff --git a/doxygen/input/doc_mainpage.h b/doxygen/input/doc_mainpage.h
index 87b5041..add75f7 100644
--- a/doxygen/input/doc_mainpage.h
+++ b/doxygen/input/doc_mainpage.h
@@ -1,6 +1,9 @@
 /**
- * @file
- * Main page documentation file.
+ * \file doc_mainpage.h
+ *
+ * \brief Main page documentation file.
+ */
+/*
  *
  *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
  *  SPDX-License-Identifier: Apache-2.0