arm: green-mango: Rework USB OTG settings

Compile support into the kernel (no modules). Use the newer
configfs-based approach.

Author: frederikaalund

arch/arm/configs/green_mango_defconfig

@@ -177,11 +177,11 @@ CONFIG_NOP_USB_XCEIV=y
 CONFIG_USB_ULPI=y
 CONFIG_USB_GADGET=y
 CONFIG_USB_GADGET_XILINX=y
-CONFIG_USB_CONFIGFS=m
+CONFIG_USB_CONFIGFS=y
 CONFIG_USB_CONFIGFS_MASS_STORAGE=y
-CONFIG_USB_ZERO=m
 CONFIG_USB_USBNET=y
 CONFIG_USB_NET_AX8817X=y
+CONFIG_USB_OTG=y
 CONFIG_MMC=y
 CONFIG_MMC_SDHCI=y
 CONFIG_MMC_SDHCI_PLTFM=y