drivers/mtd: Move conditional compilation to Makefile

rename CFG_FLASH_CFI_DRIVER to CONFIG_FLASH_CFI_DRIVER

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/board/prodrive/pdnb3/flash.c b/board/prodrive/pdnb3/flash.c
index 518ea9c..0786324 100644
--- a/board/prodrive/pdnb3/flash.c
+++ b/board/prodrive/pdnb3/flash.c
@@ -24,7 +24,7 @@
 #include <common.h>
 #include <asm/arch/ixp425.h>
 
-#if !defined(CFG_FLASH_CFI_DRIVER)
+#if !defined(CONFIG_FLASH_CFI_DRIVER)
 
 /*
  * include common flash code (for esd boards)
@@ -86,4 +86,4 @@
 	return size;
 }
 
-#endif /* CFG_FLASH_CFI_DRIVER */
+#endif /* CONFIG_FLASH_CFI_DRIVER */