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/PM828.h b/include/configs/PM828.h
index abf593c..96c0edf 100644
--- a/include/configs/PM828.h
+++ b/include/configs/PM828.h
@@ -183,7 +183,7 @@
 /*
  * Disk-On-Chip configuration
  */
-#define CFG_NAND_LEGACY
+#define CONFIG_NAND_LEGACY
 
 #define CFG_DOC_SHORT_TIMEOUT
 #define CFG_MAX_DOC_DEVICE	1	/* Max number of DOC devices	*/