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/icecube/flash.c b/board/icecube/flash.c
index 15e86d3..2d4026a 100644
--- a/board/icecube/flash.c
+++ b/board/icecube/flash.c
@@ -23,7 +23,7 @@
 
 #include <common.h>
 
-#ifndef CFG_FLASH_CFI_DRIVER
+#ifndef CONFIG_FLASH_CFI_DRIVER
 flash_info_t	flash_info[CFG_MAX_FLASH_BANKS]; /* info for FLASH chips	*/
 
 /* NOTE - CONFIG_FLASH_16BIT means the CPU interface is 16-bit, it
@@ -490,4 +490,4 @@
 
 	return (res);
 }
-#endif /*CFG_FLASH_CFI_DRIVER*/
+#endif /*CONFIG_FLASH_CFI_DRIVER*/