Fix quoting problem (preboot setting) in many board config files.

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/include/configs/CU824.h b/include/configs/CU824.h
index 68e816a..8b50087 100644
--- a/include/configs/CU824.h
+++ b/include/configs/CU824.h
@@ -50,7 +50,7 @@
 #define CONFIG_BAUDRATE		9600
 #define CFG_BAUDRATE_TABLE	{ 9600, 19200, 38400, 57600, 115200 }
 
-#define CONFIG_PREBOOT	"echo;echo Type \"run flash_nfs\" to mount root filesystem over NFS;echo"
+#define CONFIG_PREBOOT	"echo;echo Type \\\"run flash_nfs\\\" to mount root filesystem over NFS;echo"
 
 #define CONFIG_BOOTCOMMAND	"bootm FE020000"	/* autoboot command	*/
 #define CONFIG_BOOTDELAY	5