this changes acm_probe() to using the proper union descriptor.
It contains the workaround David suggested. Please apply.

  - fix probing to use cdc union descriptor

Signed-off-by: Oliver Neukum <oliver@neukum.name>
Signed-off-by: Vojtech Pavlik <vojtech@suse.cz>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>