usbgadget was initially enabled in the hope to support gadget mode
as it seems to be supported by the hardware.
However, it currently breaks things and doesn't work anyway, so
remove the usbgadget feature.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@44407 3c298f89-4303-0410-b956-a3cf2f4a3e73