ARM: pxa: remove unused pxa3xx-ulpi

This was only used by the cm-x300 board, which is now gone.

Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: linux-usb@vger.kernel.org
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>