kernel: add missing symbol

Signed-off-by: John Crispin <blogic@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@45218 3c298f89-4303-0410-b956-a3cf2f4a3e73

target/linux/generic/config-3.18

@@ -3916,6 +3916,7 @@ CONFIG_TINY_RCU=y
 # CONFIG_TI_DAVINCI_MDIO is not set
 # CONFIG_TI_ST is not set
 # CONFIG_TLAN is not set
+# CONFIG_TWL4030_MADC is not set
 # CONFIG_TMD_HERMES is not set
 # CONFIG_TMP006 is not set
 CONFIG_TMPFS=y