Fix IAR warnings

IAR was warning that conditional execution could bypass initialisation of
variables, although those same variables were not used uninitialised. Fix
this along with some other IAR warnings.

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
diff --git a/ChangeLog.d/fix-iar-warnings.txt b/ChangeLog.d/fix-iar-warnings.txt
index 244e863..8a30132 100644
--- a/ChangeLog.d/fix-iar-warnings.txt
+++ b/ChangeLog.d/fix-iar-warnings.txt
@@ -1,2 +1,2 @@
 Bugfix
-   * Fix IAR compiler warnings. Contributed by Glenn Strauss in #3835.
+   * Fix IAR compiler warnings. Fixes #6924.