USB: atmel-usba-udc : fix control out requests.

usbtest #14 was failing with "udc: ep0: TXCOMP: Invalid endpoint state 2, halting endpoint..."
This occured since ep0 is bidirectional and ep->is_in is not valid (must always use ep->state)

Signed-off-by: Martin Fuzzey <mfuzzey@gmail.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>