Fix compile problem with new env code.

Signed-off-by: Wolfgang Denk <wd@denx.de>

tools/env/fw_env.c

@@ -35,6 +35,7 @@
 #ifdef MTD_OLD
 # include <linux/mtd/mtd.h>
 #else
+# define  __user	/* nothing */
 # include <mtd/mtd-user.h>
 #endif