arm/km: make local function startup_allowed static

Signed-off-by: NHolger Brunck <holger.brunck@keymile.com>
Acked-by: NValentin Longchamp <valentin.longchamp@keymile.com>

board/keymile/km_arm/km_arm.c

@@ -102,7 +102,7 @@ static const u32 kwmpp_config[] = {
 /*
  * Wait for startup OK from mgcoge3ne
  */
-int startup_allowed(void)
+static int startup_allowed(void)
 {
 	unsigned char buf;