ColdFire: Remove save env in NAND support for M54418TWR board.

This patch remove the env saving in NAND as so far the
NAND driver is not ported to the M54418TWR platform.
Signed-off-by: NJason Jin <Jason.jin@freescale.com>

include/configs/M54418TWR.h

@@ -350,7 +350,7 @@
 #endif
 #if defined(CONFIG_SYS_NAND_BOOT)
 #define CONFIG_SYS_NO_FLASH
-#define CONFIG_ENV_IS_IN_NAND	1
+#define CONFIG_ENV_IS_NOWHERE
 #define CONFIG_ENV_OFFSET	0x80000
 #define CONFIG_ENV_SIZE	0x20000
 #define CONFIG_ENV_SECT_SIZE	0x20000