usb: gadget: Convert USB_ETHER to Kconfig

The USB Ethernet gadget option has not yet been moved to Kconfig, let's
deal with that.

Reviewed-by: Ɓukasz Majewski <lukma@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
diff --git a/configs/h2200_defconfig b/configs/h2200_defconfig
index 5d2189e..8b4deae 100644
--- a/configs/h2200_defconfig
+++ b/configs/h2200_defconfig
@@ -29,3 +29,6 @@
 # CONFIG_CMD_MISC is not set
 # CONFIG_MMC is not set
 CONFIG_PXA_SERIAL=y
+CONFIG_USB=y
+CONFIG_USB_GADGET=y
+CONFIG_USB_ETHER=y