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/sniper_defconfig b/configs/sniper_defconfig
index c75b1ba..a3bae56 100644
--- a/configs/sniper_defconfig
+++ b/configs/sniper_defconfig
@@ -40,6 +40,7 @@
 CONFIG_USB=y
 CONFIG_USB_MUSB_GADGET=y
 CONFIG_USB_MUSB_OMAP2PLUS=y
+CONFIG_TWL4030_USB=y
 CONFIG_USB_GADGET=y
 CONFIG_USB_GADGET_MANUFACTURER="Texas Instruments"
 CONFIG_USB_GADGET_VENDOR_NUM=0x0451