Remove unused variables

Remove unused variables -- they cause warnings (and errors with
-Werror) when building with clang 3.4.

Change-Id: I03fff9b1b9d620763f41c8b31a19c4724726739c
Signed-off-by: Bernhard Rosenkränzer <Bernhard.Rosenkranzer@linaro.org>
diff --git a/config.c b/config.c
index 61a4ebb..b82ac6c 100644
--- a/config.c
+++ b/config.c
@@ -154,7 +154,7 @@
  * does dns lookups to set the plat subnet or exits on failure, waits forever for a dns response with a query backoff timer
  */
 void dns64_detection() {
-  int i, backoff_sleep, status;
+  int backoff_sleep, status;
   struct in6_addr tmp_ptr;
 
   backoff_sleep = 1;