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/TQM85xx.h b/include/configs/TQM85xx.h
index 964193f..d84554e 100644
--- a/include/configs/TQM85xx.h
+++ b/include/configs/TQM85xx.h
@@ -345,7 +345,7 @@
 /* NAND FLASH */
 #ifdef CONFIG_NAND
 
-#undef CFG_NAND_LEGACY
+#undef CONFIG_NAND_LEGACY
 
 #define CONFIG_NAND_FSL_UPM	1