[PATCH] USB: fix acm trouble with terminals

This patch fixes lost LF when ACM device is used with getty/login/bash,
in case of a modem which takes calls.

Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Oliver Neukum <oliver@neukum.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>