ralink: mt7621 was missing a symbol that made the CC builder fail

Signed-off-by: John Crispin <[email protected]>

SVN-Revision: 43629

target/linux/ramips/mt7621/config-3.14

@@ -207,3 +207,4 @@ CONFIG_WATCHDOG_CORE=y
 CONFIG_WEAK_ORDERING=y
 CONFIG_XPS=y
 CONFIG_ZONE_DMA_FLAG=0
+# CONFIG_MTK_MTD_NAND is not set