USB: list atmel husb2_udc gadget controller

This identifies the driver for the Atmel HUSB2 Device Controller,
as integrated into the first AVR32 chip, the AT32AP700.

From: Hvard Skinnemoen <hskinnemoen@atmel.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>