km/common: stop u-boot only if someone press <SPACE>

To prevent u-boot to stop accidently e.g. due to line noise on the
serial line, we now use the option CONFIG_AUTOBOOT_KEYED. We choose the
<SPACE> key for this.
Signed-off-by: NHolger Brunck <holger.brunck@keymile.com>
Signed-off-by: NValentin Longchamp <valentin.longchamp@keymile.com>
Reviewed-by: NHeiko Schocher <hs@denx.de>

include/configs/km/keymile-common.h

@@ -56,6 +56,10 @@
 #define CONFIG_LOADS_ECHO
 #define CONFIG_SYS_LOADS_BAUD_CHANGE
 
+#define CONFIG_AUTOBOOT_KEYED
+#define CONFIG_AUTOBOOT_PROMPT "Hit <SPACE> key to stop autoboot in %2ds\n"
+#define CONFIG_AUTOBOOT_STOP_STR        " "
+
 /* Support the IVM EEprom */
 #define	CONFIG_SYS_IVM_EEPROM_ADR	0x50
 #define CONFIG_SYS_IVM_EEPROM_MAX_LEN	0x400