Cleanup the headers

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
diff --git a/regulator.c b/regulator.c
index 4151fdb..c8cbe2d 100644
--- a/regulator.c
+++ b/regulator.c
@@ -156,7 +156,7 @@
 
 }
 
-int regulator_display(void)
+static int regulator_display(void)
 {
 	int ret, line = 0;