drivers/mtd/nand: Move conditional compilation to Makefile

rename CFG_NAND_LEGACY to CONFIG_NAND_LEGACY

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/include/configs/NETTA2.h b/include/configs/NETTA2.h
index b8c4848..9a1f1d6 100644
--- a/include/configs/NETTA2.h
+++ b/include/configs/NETTA2.h
@@ -503,7 +503,7 @@
 /****************************************************************/
 
 /* NAND */
-#define CFG_NAND_LEGACY
+#define CONFIG_NAND_LEGACY
 #define CFG_NAND_BASE		NAND_BASE
 #define CONFIG_MTD_NAND_ECC_JFFS2
 #define CONFIG_MTD_NAND_VERIFY_WRITE