arm/km: make local function startup_allowed static

Signed-off-by: Holger Brunck <holger.brunck@keymile.com>
Acked-by: Valentin Longchamp <valentin.longchamp@keymile.com>
diff --git a/board/keymile/km_arm/km_arm.c b/board/keymile/km_arm/km_arm.c
index 946cbed..c104896 100644
--- a/board/keymile/km_arm/km_arm.c
+++ b/board/keymile/km_arm/km_arm.c
@@ -102,7 +102,7 @@
 /*
  * Wait for startup OK from mgcoge3ne
  */
-int startup_allowed(void)
+static int startup_allowed(void)
 {
 	unsigned char buf;