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/CPU87.h b/include/configs/CPU87.h
index 3879d9b..d325c4d 100644
--- a/include/configs/CPU87.h
+++ b/include/configs/CPU87.h
@@ -191,7 +191,7 @@
 #endif
 
 
-#define CFG_NAND_LEGACY
+#define CONFIG_NAND_LEGACY
 
 /*
  * Miscellaneous configurable options