AuditLog: Improve code quality

This patch fix the following things:
* add const keyword when mutability is not required
* cast unused parameters to void to be more explicit
* add parenthesis for better readability of some expressions
* check the returning value of functions
* avoid implicit casting by using matching types

Change-Id: Ia3d8dfb34d6a0bfb36f0cfca1fe6db9a1820ca33
Signed-off-by: Hugues de Valon <hugues.devalon@arm.com>
diff --git a/interface/src/tfm_audit_api.c b/interface/src/tfm_audit_api.c
index 2a69582..0770bd0 100644
--- a/interface/src/tfm_audit_api.c
+++ b/interface/src/tfm_audit_api.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, Arm Limited. All rights reserved.
+ * Copyright (c) 2018-2019, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  *
@@ -70,5 +70,6 @@
      * of the Non-Secure interface, always directly return an error without
      * routing the call to TF-M in the Secure world
      */
+    (void)record;
     return PSA_AUDIT_ERR_NOT_SUPPORTED;
 }