arm/km: fix u-boot update functionality

Due to the new I2C framework we need to adapt the u-boot update
function. Due to the new framework all i2c leafs behind a mux are
present in the system and not only those who are defined and used. So it
is bus number 5 after the rework.

Signed-off-by: Holger Brunck <holger.brunck@keymile.com>
cc: Heiko Schocher <hs@denx.de>
cc: Prafulla Wadaskar <prafulla@marvell.com>

include/configs/km/km_arm.h

@@ -295,7 +295,8 @@ int get_scl(void);
 #else
 #define CONFIG_KM_NEW_ENV						\
 	"newenv=setenv addr 0x100000 && "				\
-		"i2c dev 1; mw.b ${addr} 0 4 && "			\
+		"i2c dev " __stringify(CONFIG_I2C_ENV_EEPROM_BUS) "; "  \
+		"mw.b ${addr} 0 4 && "					\
 		"eeprom write " __stringify(CONFIG_SYS_DEF_EEPROM_ADDR)	\
 		" ${addr} " __stringify(CONFIG_ENV_OFFSET) " 4 && "	\
 		"eeprom write " __stringify(CONFIG_SYS_DEF_EEPROM_ADDR)	\