USB: add atmel_usba_udc driver

This is a driver for the Atmel USBA UDC which can be found integrated
on AT32AP700x AVR32 processors. For hardware documentation, please see
the AT32AP7000 data sheet:

http://www.atmel.com/dyn/resources/prod_documents/doc32003.pdf

This is a dual speed controller (connects at high or full speed).
The driver supports up to 7 control, bulk, interrupt and isochronous
endpoints with some constraints. Bulk, interrupt and isochronous
transfers are driven by DMA.

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