Consider CONFIG_ZERO_BOOTDELAY_CHECK when CONFIG_AUTOBOOT_KEYED is set

When CONFIG_ZERO_BOOTDELAY_CHECK is not defined, bootdelay==0
prevents the check for console input (as stated in README.autoboot).
This must also work in CONFIG_AUTOBOOT_KEYED mode.

Signed-off-by: Dirk Eibach <eibach@gdsys.de>
diff --git a/common/main.c b/common/main.c
index 9405922..81984ac 100644
--- a/common/main.c
+++ b/common/main.c
@@ -114,6 +114,11 @@
 	u_int presskey_max = 0;
 	u_int i;
 
+#ifndef CONFIG_ZERO_BOOTDELAY_CHECK
+	if (bootdelay == 0)
+		return 0;
+#endif
+
 #  ifdef CONFIG_AUTOBOOT_PROMPT
 	printf(CONFIG_AUTOBOOT_PROMPT);
 #  endif