Clean up more warnings

Change-Id: I8fc1a0a55a421ee3dbdcb484fbea71192359471d
diff --git a/include/platform/timer.h b/include/platform/timer.h
index f2085c0..b868b18 100644
--- a/include/platform/timer.h
+++ b/include/platform/timer.h
@@ -30,6 +30,8 @@
 void mdelay(unsigned msecs);
 void udelay(unsigned usecs);
 
+uint32_t platform_tick_rate(void);
+
 
 #endif