Convert CONFIG_TWL4030_USB to Kconfig

This converts the following to Kconfig:
   CONFIG_TWL4030_USB

Signed-off-by: Adam Ford <aford173@gmail.com>
diff --git a/configs/igep00x0_defconfig b/configs/igep00x0_defconfig
index d8ece6b..22dbc70 100644
--- a/configs/igep00x0_defconfig
+++ b/configs/igep00x0_defconfig
@@ -43,6 +43,7 @@
 CONFIG_USB=y
 CONFIG_USB_MUSB_UDC=y
 CONFIG_USB_OMAP3=y
+CONFIG_TWL4030_USB=y
 CONFIG_FAT_WRITE=y
 CONFIG_BCH=y
 CONFIG_OF_LIBFDT=y