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/nand.h b/include/nand.h
index 764e9f9..4c2b76d 100644
--- a/include/nand.h
+++ b/include/nand.h
@@ -26,7 +26,7 @@
 
 extern void nand_init(void);
 
-#ifndef CFG_NAND_LEGACY
+#ifndef CONFIG_NAND_LEGACY
 #include <linux/mtd/compat.h>
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/nand.h>
@@ -128,5 +128,5 @@
 
 __attribute__((noreturn)) void nand_boot(void);
 
-#endif /* !CFG_NAND_LEGACY */
+#endif /* !CONFIG_NAND_LEGACY */
 #endif