Cleanup the headers

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
diff --git a/sensor.c b/sensor.c
index 20602c0..399605b 100644
--- a/sensor.c
+++ b/sensor.c
@@ -250,7 +250,7 @@
 	return ret;
 }
 
-int sensor_display(void)
+static int sensor_display(void)
 {
 	int ret, line = 0;