contiki: Fix BYTE_ORDER setting to UIP_BYTE_ORDER

There was the wrong #ifdef which prevented setting BYTE_ORDER.
It was working for LITTLE_ENDIAN platforms as defaulting to it.

Change-Id: Ia8028c654f04f92e43b8e0ad24e1a18177a975e7
Signed-off-by: Gaëtan Harter <gaetan.harter@inria.fr>

platform-specific/platform.h

diff --git a/platform-specific/platform.h b/platform-specific/platform.h
index 83c46ea..42b8bc9 100644
--- a/platform-specific/platform.h
+++ b/platform-specific/platform.h
@@ -77,7 +77,7 @@
 #ifndef BIG_ENDIAN
 #define BIG_ENDIAN    UIP_BIG_ENDIAN
 #endif
-#ifndef UIP_BYTE_ORDER
+#ifndef BYTE_ORDER
 #define BYTE_ORDER    UIP_BYTE_ORDER
 #endif