USB: ezusb: unexport some functions that aren't being used

USB: ezusb: unexport some functions that aren't being used

When the ezusb code was split out, support was added for the fx2 chip
type, but no one is using these functions, so comment it out.  If
someone needs it, it can be added back in the future.

Also properly include <linux/usb/ezusb.h> into the ezusb.c file, to
ensure we catch any function prototype mis-matches

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: René Bürgel <rene.buergel@sohard.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>